webpki

webpki::aki::root-with-aki-missing-keyidentifier

Produces the following invalid chain:

root -> EE

The root cert incudes the authorityKeyIdentifier extension but without the keyIdentifier field, which is required under CABF:

7.1.2.1.3 Root CA Authority Key Identifier Field Description ... keyIdentifier MUST be present. MUST be identical to the subjectKeyIdentifier field.

Expected result	Validation kind	Validation time	Features	Importance	Conflicts	Download
FAILURE	SERVER	N/A	N/A	undetermined	N/A	PEM bundle

Harness	Result	Context
gnutls-certtool-3.7.3	❌ (unexpected success)	Chain verification output: Verified. The certificate is trusted.
openssl-3.2.1	❌ (unexpected success)	N/A
rust-webpki	❌ (unexpected success)	N/A
openssl-3.0.13	❌ (unexpected success)	N/A
pyca-cryptography-42.0.5	✅	validation failed: CandidatesExhausted(Other("authorityKeyIdentifier must contain keyIdentifier"))
openssl-1.1	❌ (unexpected success)	N/A
gocryptox509-go1.22.2	❌ (unexpected success)	validation: chain built
openssl-3.1.5	❌ (unexpected success)	N/A
certvalidator-0.11.1	❌ (unexpected success)	N/A
rustls-webpki	❌ (unexpected success)	N/A

webpki::aki::root-with-aki-authoritycertissuer

Produces the following invalid chain:

root -> EE

The root cert includes the authorityKeyIdentifier extension with the authorityCertIssuer field, which is forbidden under CABF:

7.1.2.1.3 Root CA Authority Key Identifier Field Description ... authorityCertIssuer MUST NOT be present

Expected result	Validation kind	Validation time	Features	Importance	Conflicts	Download
FAILURE	SERVER	N/A	N/A	undetermined	N/A	PEM bundle

Harness	Result	Context
gnutls-certtool-3.7.3	❌ (unexpected success)	Chain verification output: Verified. The certificate is trusted.
openssl-3.2.1	❌ (unexpected success)	N/A
rust-webpki	❌ (unexpected success)	N/A
openssl-3.0.13	❌ (unexpected success)	N/A
pyca-cryptography-42.0.5	✅	validation failed: CandidatesExhausted(Other("authorityKeyIdentifier must not contain authorityCertIssuer"))
openssl-1.1	❌ (unexpected success)	N/A
gocryptox509-go1.22.2	❌ (unexpected success)	validation: chain built
openssl-3.1.5	❌ (unexpected success)	N/A
certvalidator-0.11.1	❌ (unexpected success)	N/A
rustls-webpki	❌ (unexpected success)	N/A

webpki::aki::root-with-aki-authoritycertserialnumber

Produces the following invalid chain:

root -> EE

The root cert includes the authorityKeyIdentifier extension with the authorityCertSerialNumber field, which is forbidden under the [CA/B BR profile]:

7.1.2.1.3 Root CA Authority Key Identifier Field Description ... authorityCertSerialNumber MUST NOT be present

Expected result	Validation kind	Validation time	Features	Importance	Conflicts	Download
FAILURE	SERVER	N/A	N/A	undetermined	N/A	PEM bundle

Harness	Result	Context
gnutls-certtool-3.7.3	❌ (unexpected success)	Chain verification output: Verified. The certificate is trusted.
openssl-3.2.1	❌ (unexpected success)	N/A
rust-webpki	❌ (unexpected success)	N/A
openssl-3.0.13	❌ (unexpected success)	N/A
pyca-cryptography-42.0.5	✅	validation failed: CandidatesExhausted(Other("authorityKeyIdentifier must not contain authorityCertSerialNumber"))
openssl-1.1	❌ (unexpected success)	N/A
gocryptox509-go1.22.2	❌ (unexpected success)	validation: chain built
openssl-3.1.5	❌ (unexpected success)	N/A
certvalidator-0.11.1	❌ (unexpected success)	N/A
rustls-webpki	❌ (unexpected success)	N/A

webpki::aki::root-with-aki-all-fields

Produces the following invalid chain:

root -> EE

The root cert includes the authorityKeyIdentifier extension with the authorityCertIssuer and authorityCertSerialNumber fields, which is forbidden under CABF:

7.1.2.1.3 Root CA Authority Key Identifier Field Description ... authorityCertIssuer MUST NOT be present authorityCertSerialNumber MUST NOT be present

Expected result	Validation kind	Validation time	Features	Importance	Conflicts	Download
FAILURE	SERVER	N/A	N/A	undetermined	N/A	PEM bundle

Harness	Result	Context
gnutls-certtool-3.7.3	❌ (unexpected success)	Chain verification output: Verified. The certificate is trusted.
openssl-3.2.1	❌ (unexpected success)	N/A
rust-webpki	❌ (unexpected success)	N/A
openssl-3.0.13	❌ (unexpected success)	N/A
pyca-cryptography-42.0.5	✅	validation failed: CandidatesExhausted(Other("authorityKeyIdentifier must not contain authorityCertIssuer"))
openssl-1.1	❌ (unexpected success)	N/A
gocryptox509-go1.22.2	❌ (unexpected success)	validation: chain built
openssl-3.1.5	❌ (unexpected success)	N/A
certvalidator-0.11.1	❌ (unexpected success)	N/A
rustls-webpki	❌ (unexpected success)	N/A

webpki::aki::root-with-aki-ski-mismatch

Produces the following invalid chain:

root -> EE

The root cert is self-signed contains an authorityKeyIdentifier, but the keyIdentifier field doesn't match the subjectKeyIdentifier field as required under CABF.

Expected result	Validation kind	Validation time	Features	Importance	Conflicts	Download
FAILURE	SERVER	N/A	N/A	undetermined	N/A	PEM bundle

Harness	Result	Context
gnutls-certtool-3.7.3	❌ (unexpected success)	Chain verification output: Verified. The certificate is trusted.
openssl-3.2.1	❌ (unexpected success)	N/A
rust-webpki	❌ (unexpected success)	N/A
openssl-3.0.13	❌ (unexpected success)	N/A
pyca-cryptography-42.0.5	🚧	testcase skipped (explicitly unsupported case)
openssl-1.1	❌ (unexpected success)	N/A
gocryptox509-go1.22.2	❌ (unexpected success)	validation: chain built
openssl-3.1.5	❌ (unexpected success)	N/A
certvalidator-0.11.1	❌ (unexpected success)	N/A
rustls-webpki	❌ (unexpected success)	N/A

webpki::eku::ee-anyeku

Produces the following invalid chain:

root -> EE

This chain is correctly constructed, but the EE cert contains an Extended Key Usage extension that contains anyExtendedKeyUsage, which is explicitly forbidden under CABF 7.1.2.7.10.

Expected result	Validation kind	Validation time	Features	Importance	Conflicts	Download
FAILURE	SERVER	N/A	pedantic-webpki-eku	undetermined	N/A	PEM bundle

Harness	Result	Context
gnutls-certtool-3.7.3	🚧	custom EKUs not yet supported
openssl-3.2.1	❌ (unexpected success)	N/A
rust-webpki	❌ (unexpected success)	N/A
openssl-3.0.13	❌ (unexpected success)	N/A
pyca-cryptography-42.0.5	🚧	testcase skipped (explicit unsupported feature)
openssl-1.1	❌ (unexpected success)	N/A
gocryptox509-go1.22.2	❌ (unexpected success)	validation: chain built
openssl-3.1.5	❌ (unexpected success)	N/A
certvalidator-0.11.1	❌ (unexpected success)	N/A
rustls-webpki	❌ (unexpected success)	N/A

webpki::eku::ee-critical-eku

Produces the following invalid chain:

root -> EE

This chain is correctly constructed, but the EE has an extKeyUsage extension marked as critical, which is forbidden per CABF 7.1.2.7.6.

Expected result	Validation kind	Validation time	Features	Importance	Conflicts	Download
FAILURE	SERVER	N/A	pedantic-webpki-eku	undetermined	N/A	PEM bundle

Harness	Result	Context
gnutls-certtool-3.7.3	🚧	custom EKUs not yet supported
openssl-3.2.1	❌ (unexpected success)	N/A
rust-webpki	❌ (unexpected success)	N/A
openssl-3.0.13	❌ (unexpected success)	N/A
pyca-cryptography-42.0.5	🚧	testcase skipped (explicit unsupported feature)
openssl-1.1	❌ (unexpected success)	N/A
gocryptox509-go1.22.2	❌ (unexpected success)	validation: chain built
openssl-3.1.5	❌ (unexpected success)	N/A
certvalidator-0.11.1	❌ (unexpected success)	N/A
rustls-webpki	❌ (unexpected success)	N/A

webpki::eku::ee-without-eku

Produces the following invalid chain:

root -> EE

This chain is correctly constructed, but the EE does not have the extKeyUsage extension, which is required per CABF 7.1.2.7.6.

Expected result	Validation kind	Validation time	Features	Importance	Conflicts	Download
FAILURE	SERVER	N/A	pedantic-webpki-eku	undetermined	rfc5280::eku::ee-without-eku	PEM bundle

Harness	Result	Context
gnutls-certtool-3.7.3	❌ (unexpected success)	Chain verification output: Verified. The certificate is trusted.
openssl-3.2.1	❌ (unexpected success)	N/A
rust-webpki	❌ (unexpected success)	N/A
openssl-3.0.13	❌ (unexpected success)	N/A
pyca-cryptography-42.0.5	🚧	testcase skipped (explicit unsupported feature)
openssl-1.1	❌ (unexpected success)	N/A
gocryptox509-go1.22.2	❌ (unexpected success)	validation: chain built
openssl-3.1.5	❌ (unexpected success)	N/A
certvalidator-0.11.1	❌ (unexpected success)	N/A
rustls-webpki	❌ (unexpected success)	N/A

webpki::eku::root-has-eku

Produces the following invalid chain:

root -> EE

The root cert includes the extKeyUsage extension, which is forbidden under CABF:

7.1.2.1.2 Root CA Extensions Extension Presence Critical ... extKeyUsage MUST NOT N

Expected result	Validation kind	Validation time	Features	Importance	Conflicts	Download
FAILURE	SERVER	N/A	pedantic-webpki-eku	undetermined	N/A	PEM bundle

Harness	Result	Context
gnutls-certtool-3.7.3	🚧	custom EKUs not yet supported
openssl-3.2.1	❌ (unexpected success)	N/A
rust-webpki	❌ (unexpected success)	N/A
openssl-3.0.13	❌ (unexpected success)	N/A
pyca-cryptography-42.0.5	🚧	testcase skipped (explicit unsupported feature)
openssl-1.1	❌ (unexpected success)	N/A
gocryptox509-go1.22.2	❌ (unexpected success)	validation: chain built
openssl-3.1.5	❌ (unexpected success)	N/A
certvalidator-0.11.1	❌ (unexpected success)	N/A
rustls-webpki	❌ (unexpected success)	N/A

webpki::nc::permitted-dns-match-noncritical

Produces the following valid chain:

root -> leaf

The root contains a NameConstraints extension with a permitted dNSName of "example.com", matching the leaf's SubjectAlternativeName. The NameConstraints extension is marked as non-critical, which would be a violation of RFC 5280, but CABF explicitly permits this as an exception to RFC 5280:

As an explicit exception from RFC 5280, this extension SHOULD be marked critical, but MAY be marked non-critical if compatibility with certain legacy applications that do not support Name Constraints is necessary.

Expected result	Validation kind	Validation time	Features	Importance	Conflicts	Download
SUCCESS	SERVER	N/A	N/A	undetermined	rfc5280::nc::permitted-dns-match-noncritical	PEM bundle

Harness	Result	Context
gnutls-certtool-3.7.3	✅	Chain verification output: Verified. The certificate is trusted.
openssl-3.2.1	✅	N/A
rust-webpki	❌ (unexpected failure)	UnknownIssuer
openssl-3.0.13	✅	N/A
pyca-cryptography-42.0.5	✅	N/A
openssl-1.1	✅	N/A
gocryptox509-go1.22.2	✅	N/A
openssl-3.1.5	✅	N/A
certvalidator-0.11.1	✅	N/A
rustls-webpki	✅	N/A

webpki::nc::intermediate-permitted-excluded-subtrees-both-null

Produces the following invalid chain:

root -> intermediate -> leaf

The intermediate contains a NameConstraints extension with ASN.1 NULL for both permittedSubtrees and excludedSubtrees, which is forbidden under CABF 7.1.2.5.2.

Expected result	Validation kind	Validation time	Features	Importance	Conflicts	Download
FAILURE	SERVER	N/A	N/A	undetermined	N/A	PEM bundle

Harness	Result	Context
gnutls-certtool-3.7.3	❌ (unexpected success)	Chain verification output: Verified. The certificate is trusted.
openssl-3.2.1	❌ (unexpected success)	N/A
rust-webpki	❌ (unexpected success)	N/A
openssl-3.0.13	❌ (unexpected success)	N/A
pyca-cryptography-42.0.5	✅	validation failed: CandidatesExhausted(Other("nameConstraints must have non-empty permittedSubtrees or excludedSubtrees"))
openssl-1.1	❌ (unexpected success)	N/A
gocryptox509-go1.22.2	✅	N/A
openssl-3.1.5	❌ (unexpected success)	N/A
certvalidator-0.11.1	✅	The path could not be validated because intermediate certificate 1 contains the following unsupported critical extension: name_constraints
rustls-webpki	❌ (unexpected success)	N/A

webpki::nc::intermediate-permitted-excluded-subtrees-both-empty-sequences

Produces the following invalid chain:

root -> intermediate -> leaf

The intermediate contains a NameConstraints extension with empty sequences for both permittedSubtrees and excludedSubtrees, which is forbidden under CABF 7.1.2.5.2.

Expected result	Validation kind	Validation time	Features	Importance	Conflicts	Download
FAILURE	SERVER	N/A	N/A	undetermined	N/A	PEM bundle

Harness	Result	Context
gnutls-certtool-3.7.3	❌ (unexpected success)	Chain verification output: Verified. The certificate is trusted.
openssl-3.2.1	❌ (unexpected success)	N/A
rust-webpki	✅	UnknownIssuer
openssl-3.0.13	❌ (unexpected success)	N/A
pyca-cryptography-42.0.5	✅	validation failed: CandidatesExhausted(Other("nameConstraints must have non-empty permittedSubtrees or excludedSubtrees"))
openssl-1.1	❌ (unexpected success)	N/A
gocryptox509-go1.22.2	✅	N/A
openssl-3.1.5	❌ (unexpected success)	N/A
certvalidator-0.11.1	✅	The path could not be validated because intermediate certificate 1 contains the following unsupported critical extension: name_constraints
rustls-webpki	❌ (unexpected success)	N/A

webpki::san::exact-dns-san

Produces a chain with a valid EE cert for example.com.

This EE cert contains a Subject Alternative Name with the dNSName "example.com". This should verify successfully against the domain "example.com", per RFC 6125 6.4.1.

Expected result	Validation kind	Validation time	Features	Importance	Conflicts	Download
SUCCESS	SERVER	N/A	N/A	undetermined	N/A	PEM bundle

Harness	Result	Context
gnutls-certtool-3.7.3	✅	Chain verification output: Verified. The certificate is trusted.
openssl-3.2.1	✅	N/A
rust-webpki	✅	N/A
openssl-3.0.13	✅	N/A
pyca-cryptography-42.0.5	✅	N/A
openssl-1.1	✅	N/A
gocryptox509-go1.22.2	✅	N/A
openssl-3.1.5	✅	N/A
certvalidator-0.11.1	✅	N/A
rustls-webpki	✅	N/A

webpki::san::exact-localhost-ip-san

Produces a chain with a valid EE cert, for IP 127.0.0.1, i.e. localhost.

Expected result	Validation kind	Validation time	Features	Importance	Conflicts	Download
SUCCESS	SERVER	N/A	N/A	undetermined	N/A	PEM bundle

Harness	Result	Context
gnutls-certtool-3.7.3	✅	Chain verification output: Verified. The certificate is trusted.
openssl-3.2.1	✅	N/A
rust-webpki	🚧	implementation requires DNS peer names
openssl-3.0.13	✅	N/A
pyca-cryptography-42.0.5	✅	N/A
openssl-1.1	✅	N/A
gocryptox509-go1.22.2	✅	N/A
openssl-3.1.5	✅	N/A
certvalidator-0.11.1	✅	N/A
rustls-webpki	✅	N/A

webpki::san::mismatch-domain-san

Produces a chain with an EE cert.

This EE cert contains a Subject Alternative Name with the dNSName example.com. This should fail to verify against the domain example2.com, per RFC 6125 6.4.1.

Each label MUST match in order for the names to be considered to match, except as supplemented by the rule about checking of wildcard labels.

Expected result	Validation kind	Validation time	Features	Importance	Conflicts	Download
FAILURE	SERVER	N/A	N/A	undetermined	N/A	PEM bundle

Harness	Result	Context
gnutls-certtool-3.7.3	✅	Chain verification output: Not verified. The certificate is NOT trusted. The name in the certificate does not match the expected.
openssl-3.2.1	✅	hostname mismatch
rust-webpki	✅	DNS name validation failed
openssl-3.0.13	✅	hostname mismatch
pyca-cryptography-42.0.5	✅	validation failed: Other("leaf certificate has no matching subjectAltName")
openssl-1.1	✅	Hostname mismatch
gocryptox509-go1.22.2	✅	N/A
openssl-3.1.5	✅	hostname mismatch
certvalidator-0.11.1	✅	The X.509 certificate provided is not valid for example2.com. Valid hostnames include: example.com
rustls-webpki	✅	subject name validation failed

webpki::san::mismatch-subdomain-san

Produces a chain with an EE cert.

This EE cert contains a Subject Alternative Name with the dNSName abc.example.com. This should fail to verify against the domain def.example.com, per RFC 6125 6.4.1.

Each label MUST match in order for the names to be considered to match, except as supplemented by the rule about checking of wildcard labels.

Expected result	Validation kind	Validation time	Features	Importance	Conflicts	Download
FAILURE	SERVER	N/A	N/A	undetermined	N/A	PEM bundle

Harness	Result	Context
gnutls-certtool-3.7.3	✅	Chain verification output: Not verified. The certificate is NOT trusted. The name in the certificate does not match the expected.
openssl-3.2.1	✅	hostname mismatch
rust-webpki	✅	DNS name validation failed
openssl-3.0.13	✅	hostname mismatch
pyca-cryptography-42.0.5	✅	validation failed: Other("leaf certificate has no matching subjectAltName")
openssl-1.1	✅	Hostname mismatch
gocryptox509-go1.22.2	✅	N/A
openssl-3.1.5	✅	hostname mismatch
certvalidator-0.11.1	✅	The X.509 certificate provided is not valid for def.example.com. Valid hostnames include: abc.example.com
rustls-webpki	✅	subject name validation failed

webpki::san::mismatch-subdomain-apex-san

Produces a chain with an EE cert.

This EE cert contains a Subject Alternative Name with the dNSName example.com. This should fail to verify against the domain abc.example.com, per RFC 6125 6.4.1.

Each label MUST match in order for the names to be considered to match, except as supplemented by the rule about checking of wildcard labels.

Expected result	Validation kind	Validation time	Features	Importance	Conflicts	Download
FAILURE	SERVER	N/A	N/A	undetermined	N/A	PEM bundle

Harness	Result	Context
gnutls-certtool-3.7.3	✅	Chain verification output: Not verified. The certificate is NOT trusted. The name in the certificate does not match the expected.
openssl-3.2.1	✅	hostname mismatch
rust-webpki	✅	DNS name validation failed
openssl-3.0.13	✅	hostname mismatch
pyca-cryptography-42.0.5	✅	validation failed: Other("leaf certificate has no matching subjectAltName")
openssl-1.1	✅	Hostname mismatch
gocryptox509-go1.22.2	✅	N/A
openssl-3.1.5	✅	hostname mismatch
certvalidator-0.11.1	✅	The X.509 certificate provided is not valid for abc.example.com. Valid hostnames include: example.com
rustls-webpki	✅	subject name validation failed

webpki::san::mismatch-apex-subdomain-san

Produces a chain with an EE cert.

This EE cert contains a Subject Alternative Name with the dNSName abc.example.com. This should fail to verify against the domain example.com, per RFC 6125 6.4.1.

Each label MUST match in order for the names to be considered to match, except as supplemented by the rule about checking of wildcard labels.

Expected result	Validation kind	Validation time	Features	Importance	Conflicts	Download
FAILURE	SERVER	N/A	N/A	undetermined	N/A	PEM bundle

Harness	Result	Context
gnutls-certtool-3.7.3	✅	Chain verification output: Not verified. The certificate is NOT trusted. The name in the certificate does not match the expected.
openssl-3.2.1	✅	hostname mismatch
rust-webpki	✅	DNS name validation failed
openssl-3.0.13	✅	hostname mismatch
pyca-cryptography-42.0.5	✅	validation failed: Other("leaf certificate has no matching subjectAltName")
openssl-1.1	✅	Hostname mismatch
gocryptox509-go1.22.2	✅	N/A
openssl-3.1.5	✅	hostname mismatch
certvalidator-0.11.1	✅	The X.509 certificate provided is not valid for example.com. Valid hostnames include: abc.example.com
rustls-webpki	✅	subject name validation failed

webpki::san::public-suffix-wildcard-san

Produces a chain with an EE cert.

This EE cert contains a Subject Alternative name with the dNSName *.com. Conformant CAs should not issue such a certificate, according to CABF:

If the FQDN portion of any Wildcard Domain Name is “registry‐controlled” or is a “public suffix”, CAs MUST refuse issuance unless the Applicant proves its rightful control of the entire Domain Namespace.

While the Baseline Requirements do not specify how clients should behave when given such a certificate, it is generally safe to assume that wildcard certificates spanning a gTLD are malicious, and clients should reject them.

Expected result	Validation kind	Validation time	Features	Importance	Conflicts	Download
FAILURE	SERVER	N/A	pedantic-public-suffix-wildcard	undetermined	N/A	PEM bundle

Harness	Result	Context
gnutls-certtool-3.7.3	✅	Chain verification output: Not verified. The certificate is NOT trusted. The name in the certificate does not match the expected.
openssl-3.2.1	✅	hostname mismatch
rust-webpki	✅	DNS name validation failed
openssl-3.0.13	✅	hostname mismatch
pyca-cryptography-42.0.5	🚧	testcase skipped (explicit unsupported feature)
openssl-1.1	✅	Hostname mismatch
gocryptox509-go1.22.2	❌ (unexpected success)	validation: chain built
openssl-3.1.5	✅	hostname mismatch
certvalidator-0.11.1	❌ (unexpected success)	N/A
rustls-webpki	✅	subject name validation failed

webpki::san::leftmost-wildcard-san

Produces a chain with an EE cert.

This EE cert contains a Subject Alternative Name with the dNSName *.example.com. This should verify successfully against the domain foo.example.com, per RFC 6125 6.4.3.

Expected result	Validation kind	Validation time	Features	Importance	Conflicts	Download
SUCCESS	SERVER	N/A	N/A	undetermined	N/A	PEM bundle

Harness	Result	Context
gnutls-certtool-3.7.3	✅	Chain verification output: Verified. The certificate is trusted.
openssl-3.2.1	✅	N/A
rust-webpki	✅	N/A
openssl-3.0.13	✅	N/A
pyca-cryptography-42.0.5	✅	N/A
openssl-1.1	✅	N/A
gocryptox509-go1.22.2	✅	N/A
openssl-3.1.5	✅	N/A
certvalidator-0.11.1	✅	N/A
rustls-webpki	✅	N/A

webpki::san::wildcard-embedded-leftmost-san

Produces a chain with an EE cert.

This EE cert contains a Subject Alternative Name with the dNSName ba*.example.com. This should fail to verify against the domain baz.example.com, per CABF.

Wildcard Domain Name: A string starting with “*.” (U+002A ASTERISK, U+002E FULL STOP) immediately followed by a Fully-Qualified Domain Name.

Expected result	Validation kind	Validation time	Features	Importance	Conflicts	Download
FAILURE	SERVER	N/A	N/A	undetermined	N/A	PEM bundle

Harness	Result	Context
gnutls-certtool-3.7.3	✅	Chain verification output: Not verified. The certificate is NOT trusted. The name in the certificate does not match the expected.
openssl-3.2.1	✅	hostname mismatch
rust-webpki	✅	DNS name validation failed
openssl-3.0.13	✅	hostname mismatch
pyca-cryptography-42.0.5	✅	validation failed: Other("leaf certificate has no matching subjectAltName")
openssl-1.1	✅	Hostname mismatch
gocryptox509-go1.22.2	✅	N/A
openssl-3.1.5	✅	hostname mismatch
certvalidator-0.11.1	❌ (unexpected success)	N/A
rustls-webpki	✅	subject name validation failed

webpki::san::wildcard-not-in-leftmost-san

Produces a chain with an EE cert.

This EE cert contains a Subject Alternative Name with the dNSName foo.*.example.com. This should fail to verify against the domain foo.bar.example.com, per RFC 6125 6.4.3.

The client SHOULD NOT attempt to match a presented identifier in which the wildcard character comprises a label other than the left-most label (e.g., do not match bar.*.example.net).

Expected result	Validation kind	Validation time	Features	Importance	Conflicts	Download
FAILURE	SERVER	N/A	N/A	undetermined	N/A	PEM bundle

Harness	Result	Context
gnutls-certtool-3.7.3	✅	Chain verification output: Not verified. The certificate is NOT trusted. The name in the certificate does not match the expected.
openssl-3.2.1	✅	hostname mismatch
rust-webpki	✅	DNS name validation failed
openssl-3.0.13	✅	hostname mismatch
pyca-cryptography-42.0.5	✅	validation failed: Other("leaf certificate has no matching subjectAltName")
openssl-1.1	✅	Hostname mismatch
gocryptox509-go1.22.2	✅	N/A
openssl-3.1.5	✅	hostname mismatch
certvalidator-0.11.1	✅	The X.509 certificate provided is not valid for foo.bar.example.com. Valid hostnames include: foo.*.example.com
rustls-webpki	✅	subject name validation failed

webpki::san::wildcard-match-across-labels-san

Produces a chain with an EE cert.

This EE cert contains a Subject Alternative Name with the dNSName *.example.com. This should fail to verify against the domain foo.bar.example.com, per RFC 6125 6.4.3.

If the wildcard character is the only character of the left-most label in the presented identifier, the client SHOULD NOT compare against anything but the left-most label of the reference identifier (e.g., *.example.com would match foo.example.com but not bar.foo.example.com or example.com).

Expected result	Validation kind	Validation time	Features	Importance	Conflicts	Download
FAILURE	SERVER	N/A	N/A	undetermined	N/A	PEM bundle

Harness	Result	Context
gnutls-certtool-3.7.3	✅	Chain verification output: Not verified. The certificate is NOT trusted. The name in the certificate does not match the expected.
openssl-3.2.1	✅	hostname mismatch
rust-webpki	✅	DNS name validation failed
openssl-3.0.13	✅	hostname mismatch
pyca-cryptography-42.0.5	✅	validation failed: Other("leaf certificate has no matching subjectAltName")
openssl-1.1	✅	Hostname mismatch
gocryptox509-go1.22.2	✅	N/A
openssl-3.1.5	✅	hostname mismatch
certvalidator-0.11.1	✅	The X.509 certificate provided is not valid for foo.bar.example.com. Valid hostnames include: *.example.com
rustls-webpki	✅	subject name validation failed

webpki::san::wildcard-embedded-ulabel-san

Produces a chain with an EE cert.

This EE cert contains a Subject Alternative Name with the dNSName xn--*-1b3c148a.example.com. This should fail to verify against the domain xn--bliss-1b3c148a.example.com, per RFC 6125 6.4.3:

... the client SHOULD NOT attempt to match a presented identifier where the wildcard character is embedded within an A-label or U-label [IDNA-DEFS] of an internationalized domain name [IDNA-PROTO].

Expected result	Validation kind	Validation time	Features	Importance	Conflicts	Download
FAILURE	SERVER	N/A	N/A	undetermined	N/A	PEM bundle

Harness	Result	Context
gnutls-certtool-3.7.3	✅	Chain verification output: Not verified. The certificate is NOT trusted. The name in the certificate does not match the expected.
openssl-3.2.1	✅	hostname mismatch
rust-webpki	✅	DNS name validation failed
openssl-3.0.13	✅	hostname mismatch
pyca-cryptography-42.0.5	✅	validation failed: Other("leaf certificate has no matching subjectAltName")
openssl-1.1	✅	Hostname mismatch
gocryptox509-go1.22.2	✅	N/A
openssl-3.1.5	✅	hostname mismatch
certvalidator-0.11.1	✅	The X.509 certificate provided is not valid for xn--bliss-1b3c148a.example.com. Valid hostnames include: *痛苦.example.com
rustls-webpki	✅	subject name validation failed

webpki::san::unicode-emoji-san

Produces a chain with an EE cert.

This EE cert contains a Subject Alternative Name with the dNSName 😜.example.com, This should fail to verify against the domain xn--628h.example.com, per RFC 5280 7.2:

IA5String is limited to the set of ASCII characters. To accommodate internationalized domain names in the current structure, conforming implementations MUST convert internationalized domain names to the ASCII Compatible Encoding (ACE) format as specified in Section 4 of RFC 3490 before storage in the dNSName field.

Expected result	Validation kind	Validation time	Features	Importance	Conflicts	Download
FAILURE	SERVER	N/A	N/A	undetermined	N/A	PEM bundle

Harness	Result	Context
gnutls-certtool-3.7.3	✅	Chain verification output: Not verified. The certificate is NOT trusted. The name in the certificate does not match the expected.
openssl-3.2.1	✅	hostname mismatch
rust-webpki	✅	DNS name validation failed
openssl-3.0.13	✅	hostname mismatch
pyca-cryptography-42.0.5	✅	validation failed: Other("leaf certificate has no matching subjectAltName")
openssl-1.1	✅	Hostname mismatch
gocryptox509-go1.22.2	✅	N/A
openssl-3.1.5	✅	hostname mismatch
certvalidator-0.11.1	✅	'ascii' codec can't decode byte 0xf0 in position 0: ordinal not in range(128)
rustls-webpki	✅	subject name validation failed

webpki::san::no-san

Produces the following invalid chain:

root -> EE

The chain is correctly constructed, but the EE cert does not have a Subject Alternative Name, which is required. This is invalid even when the Subject contains a valid domain name in its Common Name component.

Expected result	Validation kind	Validation time	Features	Importance	Conflicts	Download
FAILURE	SERVER	N/A	N/A	undetermined	N/A	PEM bundle

Harness	Result	Context
gnutls-certtool-3.7.3	❌ (unexpected success)	Chain verification output: Verified. The certificate is trusted.
openssl-3.2.1	❌ (unexpected success)	N/A
rust-webpki	✅	DNS name validation failed
openssl-3.0.13	❌ (unexpected success)	N/A
pyca-cryptography-42.0.5	✅	validation failed: Other("Certificate is missing required extension")
openssl-1.1	❌ (unexpected success)	N/A
gocryptox509-go1.22.2	✅	N/A
openssl-3.1.5	❌ (unexpected success)	N/A
certvalidator-0.11.1	❌ (unexpected success)	N/A
rustls-webpki	✅	subject name validation failed

webpki::san::san-critical-with-nonempty-subject

Produces the following invalid chain:

root -> EE

The EE cert includes a critical subjectAlternativeName extension, which is forbidden under CABF when the subject is non-empty:

If the subject field of the certificate is an empty SEQUENCE, this extension MUST be marked critical, as specified in RFC 5280, Section 4.2.1.6. Otherwise, this extension MUST NOT be marked critical.

Expected result	Validation kind	Validation time	Features	Importance	Conflicts	Download
FAILURE	SERVER	N/A	N/A	undetermined	N/A	PEM bundle

Harness	Result	Context
gnutls-certtool-3.7.3	❌ (unexpected success)	Chain verification output: Verified. The certificate is trusted.
openssl-3.2.1	❌ (unexpected success)	N/A
rust-webpki	❌ (unexpected success)	N/A
openssl-3.0.13	❌ (unexpected success)	N/A
pyca-cryptography-42.0.5	✅	validation failed: Other("EE subjectAltName MUST NOT be critical when subject is nonempty")
openssl-1.1	❌ (unexpected success)	N/A
gocryptox509-go1.22.2	❌ (unexpected success)	validation: chain built
openssl-3.1.5	❌ (unexpected success)	N/A
certvalidator-0.11.1	✅	The path could not be validated because the end-entity certificate contains the following unsupported critical extension: subject_alt_name
rustls-webpki	❌ (unexpected success)	N/A

webpki::san::san-wildcard-only

Produces the following invalid chain:

root -> EE

The EE cert contains a SAN of just DNS:*, which should be rejected.

The reason for this is subtle: CABF 3.2.2.6 notes that certs with wildcards on public suffixes should not be issued, and . (i.e. the DNS root) is effectively a public suffix. This is true even though the DNS root is not itself on the PSL.

Expected result	Validation kind	Validation time	Features	Importance	Conflicts	Download
FAILURE	SERVER	N/A	N/A	undetermined	N/A	PEM bundle

Harness	Result	Context
gnutls-certtool-3.7.3	✅	Chain verification output: Not verified. The certificate is NOT trusted. The name in the certificate does not match the expected.
openssl-3.2.1	✅	hostname mismatch
rust-webpki	✅	DNS name validation failed
openssl-3.0.13	✅	hostname mismatch
pyca-cryptography-42.0.5	✅	validation failed: Other("leaf certificate has no matching subjectAltName")
openssl-1.1	✅	Hostname mismatch
gocryptox509-go1.22.2	✅	N/A
openssl-3.1.5	✅	hostname mismatch
certvalidator-0.11.1	✅	The X.509 certificate provided is not valid for example.com. Valid hostnames include: *
rustls-webpki	✅	subject name validation failed

webpki::san::san-wildcard-only-tld

Produces the following invalid chain:

root -> EE

The EE cert contains a SAN of just DNS:*, which should be rejected.

The reason for this is subtle: CABF 3.2.2.6 notes that certs with wildcards on public suffixes should not be issued, and . (i.e. the DNS root) is effectively a public suffix. This is true even though the DNS root is not itself on the PSL.

Expected result	Validation kind	Validation time	Features	Importance	Conflicts	Download
FAILURE	SERVER	N/A	N/A	undetermined	N/A	PEM bundle

Harness	Result	Context
gnutls-certtool-3.7.3	✅	Chain verification output: Not verified. The certificate is NOT trusted. The name in the certificate does not match the expected.
openssl-3.2.1	✅	hostname mismatch
rust-webpki	✅	DNS name validation failed
openssl-3.0.13	✅	hostname mismatch
pyca-cryptography-42.0.5	✅	validation failed: Other("leaf certificate has no matching subjectAltName")
openssl-1.1	✅	Hostname mismatch
gocryptox509-go1.22.2	❌ (unexpected success)	validation: chain built
openssl-3.1.5	✅	hostname mismatch
certvalidator-0.11.1	❌ (unexpected success)	N/A
rustls-webpki	✅	subject name validation failed

webpki::explicit-curve

Produces the following invalid chain:

root -> EE

Both root and EE convey EC keys using the "explicit" curve encoding, which is forbidden under CABF 7.1.3.1.2:

The CA SHALL indicate an ECDSA key using the id‐ecPublicKey (OID: 1.2.840.10045.2.1) algorithm identifier. The parameters MUST use the namedCurve encoding.

Expected result	Validation kind	Validation time	Features	Importance	Conflicts	Download
FAILURE	SERVER	2024-03-13T00:00:00+00:00	N/A	undetermined	N/A	PEM bundle

Harness	Result	Context
gnutls-certtool-3.7.3	✅	N/A
openssl-3.2.1	✅	Certificate public key has explicit ECC parameters
rust-webpki	✅	UnknownIssuer
openssl-3.0.13	✅	Certificate public key has explicit ECC parameters
pyca-cryptography-42.0.5	✅	validation failed: CandidatesExhausted(Other("Forbidden public key algorithm: AlgorithmIdentifier { oid: DefinedByMarker(PhantomData), params: Ec(SpecifiedCurve(Sequence { data: [2, 1, 1, 48, 44, 6, 7, 42, 134, 72, 206, 61, 1, 1, 2, 33, 0, 255, 255, 255, 255, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 48, 91, 4, 32, 255, 255, 255, 255, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 252, 4, 32, 90, 198, 53, 216, 170, 58, 147, 231, 179, 235, 189, 85, 118, 152, 134, 188, 101, 29, 6, 176, 204, 83, 176, 246, 59, 206, 60, 62, 39, 210, 96, 75, 3, 21, 0, 196, 157, 54, 8, 134, 231, 4, 147, 106, 102, 120, 225, 19, 157, 38, 183, 129, 159, 126, 144, 4, 65, 4, 107, 23, 209, 242, 225, 44, 66, 71, 248, 188, 230, 229, 99, 164, 64, 242, 119, 3, 125, 129, 45, 235, 51, 160, 244, 161, 57, 69, 216, 152, 194, 150, 79, 227, 66, 226, 254, 26, 127, 155, 142, 231, 235, 74, 124, 15, 158, 22, 43, 206, 51, 87, 107, 49, 94, 206, 203, 182, 64, 104, 55, 191, 81, 245, 2, 33, 0, 255, 255, 255, 255, 0, 0, 0, 0, 255, 255, 255, 255, 255, 255, 255, 255, 188, 230, 250, 173, 167, 23, 158, 132, 243, 185, 202, 194, 252, 99, 37, 81, 2, 1, 1] })) }"))
openssl-1.1	✅	Certificate public key has explicit ECC parameters
gocryptox509-go1.22.2	✅	N/A
openssl-3.1.5	✅	Certificate public key has explicit ECC parameters
certvalidator-0.11.1	❌ (unexpected success)	N/A
rustls-webpki	✅	UnsupportedSignatureAlgorithmForPublicKey

webpki::cryptographydotio-chain

Verifies against a saved copy of cryptography.io's chain. This should trivially succeed.

Expected result	Validation kind	Validation time	Features	Importance	Conflicts	Download
SUCCESS	SERVER	2023-07-10T00:00:00+00:00	N/A	undetermined	N/A	PEM bundle

Harness	Result	Context
gnutls-certtool-3.7.3	🚧	custom key usages not supported
openssl-3.2.1	✅	N/A
rust-webpki	🚧	key_usage not supported yet
openssl-3.0.13	✅	N/A
pyca-cryptography-42.0.5	✅	N/A
openssl-1.1	✅	N/A
gocryptox509-go1.22.2	✅	N/A
openssl-3.1.5	✅	N/A
certvalidator-0.11.1	✅	N/A
rustls-webpki	🚧	key_usage not supported yet

webpki::cryptographydotio-chain-missing-intermediate

Verifies against a saved copy of cryptography.io's chain, but without its intermediates. This should trivially fail.

Expected result	Validation kind	Validation time	Features	Importance	Conflicts	Download
FAILURE	SERVER	2023-07-10T00:00:00+00:00	N/A	undetermined	N/A	PEM bundle

Harness	Result	Context
gnutls-certtool-3.7.3	🚧	custom key usages not supported
openssl-3.2.1	✅	unable to get local issuer certificate
rust-webpki	🚧	key_usage not supported yet
openssl-3.0.13	✅	unable to get local issuer certificate
pyca-cryptography-42.0.5	✅	validation failed: CandidatesExhausted(Other("all candidates exhausted with no interior errors"))
openssl-1.1	✅	unable to get local issuer certificate
gocryptox509-go1.22.2	✅	N/A
openssl-3.1.5	✅	unable to get local issuer certificate
certvalidator-0.11.1	✅	Unable to build a validation path for the certificate "Common Name: cryptography.io" - no issuer matching "Common Name: R3, Organization: Let's Encrypt, Country: US" was found
rustls-webpki	🚧	key_usage not supported yet

webpki::malformed-aia

Produces a chain with an EE cert.

This EE cert contains an Authority Information Access extension with malformed contents. This is invalid per CABF.

The AuthorityInfoAccessSyntax MUST contain one or more AccessDescriptions.

Expected result	Validation kind	Validation time	Features	Importance	Conflicts	Download
FAILURE	SERVER	N/A	N/A	undetermined	N/A	PEM bundle

Harness	Result	Context
gnutls-certtool-3.7.3	❌ (unexpected success)	Chain verification output: Verified. The certificate is trusted.
openssl-3.2.1	❌ (unexpected success)	N/A
rust-webpki	❌ (unexpected success)	N/A
openssl-3.0.13	❌ (unexpected success)	N/A
pyca-cryptography-42.0.5	✅	validation failed: Malformed(ParseError { kind: ShortData })
openssl-1.1	❌ (unexpected success)	N/A
gocryptox509-go1.22.2	✅	N/A
openssl-3.1.5	❌ (unexpected success)	N/A
certvalidator-0.11.1	✅	Insufficient data - 97 bytes requested but only 7 available while parsing asn1crypto.core.ParsableOctetString while parsing asn1crypto.x509.Extension
rustls-webpki	❌ (unexpected success)	N/A

webpki::forbidden-p192-root

Produces the following invalid chain:

root -> EE

The root cert conveys a P-192 key and signs for the EE with it, which is not permitted under the CABF's key or signature types.

Expected result	Validation kind	Validation time	Features	Importance	Conflicts	Download
FAILURE	SERVER	N/A	N/A	undetermined	N/A	PEM bundle

Harness	Result	Context
gnutls-certtool-3.7.3	✅	Chain verification output: Not verified. The certificate is NOT trusted. The certificate chain uses insecure algorithm.
openssl-3.2.1	✅	CA certificate key too weak
rust-webpki	✅	UnknownIssuer
openssl-3.0.13	✅	CA certificate key too weak
pyca-cryptography-42.0.5	✅	validation failed: CandidatesExhausted(Other("Forbidden public key algorithm: AlgorithmIdentifier { oid: DefinedByMarker(PhantomData), params: Ec(NamedCurve(ObjectIdentifier { oid: 1.2.840.10045.3.1.7 })) }"))
openssl-1.1	✅	CA certificate key too weak
gocryptox509-go1.22.2	✅	N/A
openssl-3.1.5	✅	CA certificate key too weak
certvalidator-0.11.1	❌ (unexpected success)	N/A
rustls-webpki	✅	UnsupportedSignatureAlgorithmForPublicKey

webpki::forbidden-p192-leaf

Produces the following invalid chain:

root -> EE

The EE cert conveys a P-192 key, which is not one of the permitted public keys under CABF.

Expected result	Validation kind	Validation time	Features	Importance	Conflicts	Download
FAILURE	SERVER	N/A	pedantic-webpki-subscriber-key	undetermined	N/A	PEM bundle

Harness	Result	Context
gnutls-certtool-3.7.3	✅	Chain verification output: Not verified. The certificate is NOT trusted. The certificate chain uses insecure algorithm.
openssl-3.2.1	✅	EE certificate key too weak
rust-webpki	❌ (unexpected success)	N/A
openssl-3.0.13	✅	EE certificate key too weak
pyca-cryptography-42.0.5	🚧	testcase skipped (explicit unsupported feature)
openssl-1.1	✅	EE certificate key too weak
gocryptox509-go1.22.2	✅	N/A
openssl-3.1.5	✅	EE certificate key too weak
certvalidator-0.11.1	❌ (unexpected success)	N/A
rustls-webpki	❌ (unexpected success)	N/A

webpki::forbidden-dsa-root

Produces the following invalid chain:

root -> EE

The root cert conveys a DSA-30272 key and signs for the EE with it, which is not permitted under the CABF's key or signature types.

Expected result	Validation kind	Validation time	Features	Importance	Conflicts	Download
FAILURE	SERVER	N/A	N/A	undetermined	N/A	PEM bundle

Harness	Result	Context
gnutls-certtool-3.7.3	❌ (unexpected success)	Chain verification output: Verified. The certificate is trusted.
openssl-3.2.1	❌ (unexpected success)	N/A
rust-webpki	✅	UnknownIssuer
openssl-3.0.13	❌ (unexpected success)	N/A
pyca-cryptography-42.0.5	✅	validation failed: CandidatesExhausted(Other("Forbidden public key algorithm: AlgorithmIdentifier { oid: DefinedByMarker(PhantomData), params: Ec(NamedCurve(ObjectIdentifier { oid: 1.2.840.10045.3.1.7 })) }"))
openssl-1.1	❌ (unexpected success)	N/A
gocryptox509-go1.22.2	✅	N/A
openssl-3.1.5	❌ (unexpected success)	N/A
certvalidator-0.11.1	❌ (unexpected success)	N/A
rustls-webpki	✅	UnsupportedSignatureAlgorithm

webpki::forbidden-dsa-leaf

Produces the following invalid chain:

root -> EE

The EE cert conveys a DSA key, which is not one of the permitted public keys under CABF.

Expected result	Validation kind	Validation time	Features	Importance	Conflicts	Download
FAILURE	SERVER	N/A	pedantic-webpki-subscriber-key	undetermined	N/A	PEM bundle

Harness	Result	Context
gnutls-certtool-3.7.3	❌ (unexpected success)	Chain verification output: Verified. The certificate is trusted.
openssl-3.2.1	❌ (unexpected success)	N/A
rust-webpki	❌ (unexpected success)	N/A
openssl-3.0.13	❌ (unexpected success)	N/A
pyca-cryptography-42.0.5	🚧	testcase skipped (explicit unsupported feature)
openssl-1.1	❌ (unexpected success)	N/A
gocryptox509-go1.22.2	❌ (unexpected success)	validation: chain built
openssl-3.1.5	❌ (unexpected success)	N/A
certvalidator-0.11.1	❌ (unexpected success)	N/A
rustls-webpki	❌ (unexpected success)	N/A

webpki::forbidden-weak-rsa-key-in-root

Produces the following invalid chain:

root -> EE

The root cert is signed with and conveys an RSA-1024 key, which is below the security margin (2048) required under CABF 6.1.5.

Expected result	Validation kind	Validation time	Features	Importance	Conflicts	Download
FAILURE	SERVER	N/A	N/A	undetermined	N/A	PEM bundle

Harness	Result	Context
gnutls-certtool-3.7.3	✅	Chain verification output: Not verified. The certificate is NOT trusted. The certificate chain uses insecure algorithm.
openssl-3.2.1	✅	CA certificate key too weak
rust-webpki	✅	UnknownIssuer
openssl-3.0.13	✅	CA certificate key too weak
pyca-cryptography-42.0.5	❌ (unexpected success)	N/A
openssl-1.1	✅	CA certificate key too weak
gocryptox509-go1.22.2	❌ (unexpected success)	validation: chain built
openssl-3.1.5	✅	CA certificate key too weak
certvalidator-0.11.1	❌ (unexpected success)	N/A
rustls-webpki	✅	InvalidSignatureForPublicKey

webpki::forbidden-weak-rsa-in-leaf

Produces the following invalid chain:

root -> EE

The EE cert conveys an RSA 1024 key, which is below the security margin (2048) required under CABF 6.1.5.

Expected result	Validation kind	Validation time	Features	Importance	Conflicts	Download
FAILURE	SERVER	N/A	pedantic-webpki-subscriber-key	undetermined	N/A	PEM bundle

Harness	Result	Context
gnutls-certtool-3.7.3	✅	Chain verification output: Not verified. The certificate is NOT trusted. The certificate chain uses insecure algorithm.
openssl-3.2.1	✅	EE certificate key too weak
rust-webpki	❌ (unexpected success)	N/A
openssl-3.0.13	✅	EE certificate key too weak
pyca-cryptography-42.0.5	🚧	testcase skipped (explicit unsupported feature)
openssl-1.1	✅	EE certificate key too weak
gocryptox509-go1.22.2	❌ (unexpected success)	validation: chain built
openssl-3.1.5	✅	EE certificate key too weak
certvalidator-0.11.1	❌ (unexpected success)	N/A
rustls-webpki	❌ (unexpected success)	N/A

webpki::forbidden-rsa-not-divisable-by-8-in-root

Produces the following invalid chain:

root -> EE

The root cert is signed with and conveys an RSA-2052 key, which is above the security margin (2048) but not divisible by 8, as is required under CABF 6.1.5.

Expected result	Validation kind	Validation time	Features	Importance	Conflicts	Download
FAILURE	SERVER	N/A	N/A	undetermined	N/A	PEM bundle

Harness	Result	Context
gnutls-certtool-3.7.3	✅	Chain verification output: Not verified. The certificate is NOT trusted. The certificate chain uses insecure algorithm.
openssl-3.2.1	❌ (unexpected success)	N/A
rust-webpki	❌ (unexpected success)	N/A
openssl-3.0.13	❌ (unexpected success)	N/A
pyca-cryptography-42.0.5	🚧	testcase skipped (explicitly unsupported case)
openssl-1.1	❌ (unexpected success)	N/A
gocryptox509-go1.22.2	❌ (unexpected success)	validation: chain built
openssl-3.1.5	❌ (unexpected success)	N/A
certvalidator-0.11.1	❌ (unexpected success)	N/A
rustls-webpki	❌ (unexpected success)	N/A

webpki::forbidden-rsa-key-not-divisable-by-8-in-leaf

Produces the following invalid chain:

root -> EE

The EE cert conveys an RSA-2052 key, which is above the security margin (2048) but not divisible by 8, as is required under CABF 6.1.5.

Expected result	Validation kind	Validation time	Features	Importance	Conflicts	Download
FAILURE	SERVER	N/A	pedantic-webpki-subscriber-key	undetermined	N/A	PEM bundle

Harness	Result	Context
gnutls-certtool-3.7.3	✅	Chain verification output: Not verified. The certificate is NOT trusted. The certificate chain uses insecure algorithm.
openssl-3.2.1	❌ (unexpected success)	N/A
rust-webpki	❌ (unexpected success)	N/A
openssl-3.0.13	❌ (unexpected success)	N/A
pyca-cryptography-42.0.5	🚧	testcase skipped (explicit unsupported feature)
openssl-1.1	❌ (unexpected success)	N/A
gocryptox509-go1.22.2	❌ (unexpected success)	validation: chain built
openssl-3.1.5	❌ (unexpected success)	N/A
certvalidator-0.11.1	❌ (unexpected success)	N/A
rustls-webpki	❌ (unexpected success)	N/A

webpki::v1-cert

Produces the following invalid chain:

root -> EE

This chain is correctly constructed, but the EE cert is marked with version 2 (ordinal 1) rather than version 3 (ordinal 2). This is invalid, per CABF 7.1.1:

Certificates MUST be of type X.509 v3.

Expected result	Validation kind	Validation time	Features	Importance	Conflicts	Download
FAILURE	SERVER	N/A	N/A	undetermined	N/A	PEM bundle

Harness	Result	Context
gnutls-certtool-3.7.3	❌ (unexpected success)	Chain verification output: Verified. The certificate is trusted.
openssl-3.2.1	❌ (unexpected success)	N/A
rust-webpki	✅	leaf cert: X.509 parse failed
openssl-3.0.13	❌ (unexpected success)	N/A
pyca-cryptography-42.0.5	✅	validation failed: Other("certificate must be an X509v3 certificate")
openssl-1.1	❌ (unexpected success)	N/A
gocryptox509-go1.22.2	✅	N/A
openssl-3.1.5	❌ (unexpected success)	N/A
certvalidator-0.11.1	❌ (unexpected success)	N/A
rustls-webpki	✅	leaf cert: X.509 parse failed

webpki::ee-basicconstraints-ca

Produces the following invalid chain:

root -> EE

The EE certificate has keyUsage.keyCertSign=FALSE but basicConstraints.cA=TRUE, which is explicitly forbidden under CABF 7.1.2.7.8:

cA MUST be FALSE

Expected result	Validation kind	Validation time	Features	Importance	Conflicts	Download
FAILURE	SERVER	N/A	N/A	undetermined	N/A	PEM bundle

Harness	Result	Context
gnutls-certtool-3.7.3	❌ (unexpected success)	Chain verification output: Verified. The certificate is trusted.
openssl-3.2.1	❌ (unexpected success)	N/A
rust-webpki	✅	CaUsedAsEndEntity
openssl-3.0.13	❌ (unexpected success)	N/A
pyca-cryptography-42.0.5	✅	validation failed: Other("basicConstraints.cA must not be asserted in an EE certificate")
openssl-1.1	❌ (unexpected success)	N/A
gocryptox509-go1.22.2	❌ (unexpected success)	validation: chain built
openssl-3.1.5	❌ (unexpected success)	N/A
certvalidator-0.11.1	❌ (unexpected success)	N/A
rustls-webpki	✅	CaUsedAsEndEntity

webpki::ca-as-leaf

Produces the following invalid chain:

root -> ICA

The ICA is in leaf position, despite being a CA certificate, which is explicitly forbidden under CABF 7.1.2.7.11 (keyUsage.keyCertSign must NOT be permitted) and 7.1.2.7.8 (basicConstraints.cA MUST be false`).

Expected result	Validation kind	Validation time	Features	Importance	Conflicts	Download
FAILURE	SERVER	N/A	N/A	undetermined	rfc5280::ca-as-leaf	PEM bundle

Harness	Result	Context
gnutls-certtool-3.7.3	❌ (unexpected success)	Chain verification output: Verified. The certificate is trusted.
openssl-3.2.1	❌ (unexpected success)	N/A
rust-webpki	✅	CaUsedAsEndEntity
openssl-3.0.13	❌ (unexpected success)	N/A
pyca-cryptography-42.0.5	✅	validation failed: Other("basicConstraints.cA must not be asserted in an EE certificate")
openssl-1.1	❌ (unexpected success)	N/A
gocryptox509-go1.22.2	❌ (unexpected success)	validation: chain built
openssl-3.1.5	❌ (unexpected success)	N/A
certvalidator-0.11.1	✅	The X.509 certificate provided is not valid for securing TLS connections
rustls-webpki	✅	CaUsedAsEndEntity