Advisories for Cargo/Rustls-Webpki package

bit_string_flags() in src/der.rs panics with an index-out-of-bounds when given a BIT STRING whose content is exactly [0x00] (one byte: zero padding bits, zero data bytes). This is reachable through the public API BorrowedCertRevocationList::from_der() via the issuingDistributionPoint CRL extension. Precondition: CRL checking is opt-in in rustls-webpki. This vulnerability affects only applications that explicitly pass RevocationOptions to verify_for_usage() and load CRL bytes from a source the attacker can influence. The default rustls …

Permitted subtree name constraints for DNS names were accepted for certificates asserting a wildcard name. This was incorrect because, given a name constraint of accept.example.com, *.example.com could feasibly allow a name of reject.example.com which is outside the constraint. This is very similar to CVE-2025-61727. Since name constraints are restrictions on otherwise properly-issued certificates, this bug is reachable only after signature verification and requires misissuance to exploit.

Name constraints for URI names were ignored and therefore accepted. Note this library does not provide an API for asserting URI names, and URI name constraints are otherwise not implemented. URI name constraints are now rejected unconditionally. Since name constraints are restrictions on otherwise properly-issued certificates, this bug is reachable only after signature verification and requires misissuance to exploit.

If a certificate had more than one distributionPoint, then only the first distributionPoint would be considered against each CRL's IssuingDistributionPoint distributionPoint, and then the certificate's subsequent distributionPoints would be ignored. The impact was that correct provided CRLs would not be consulted to check revocation. With UnknownStatusPolicy::Deny (the default) this would lead to incorrect but safe Error::UnknownRevocationStatus. With UnknownStatusPolicy::Allow this would lead to inappropriate acceptance of revoked certificates. This vulnerability is …

When this crate is given a pathological certificate chain to validate, it will spend CPU time exponential with the number of candidate certificates at each step of path building. Both TLS clients and TLS servers that accept client certificate are affected. We now give each path building operation a budget of 100 signature verifications. The original webpki crate is also affected, see GHSA-8qv2-5vq6-g2g7. This was previously reported in the original …