HSEC-2026-0008-2

# crypton-x509-validation and crypton-x509 do not enforce X.509 Name Constraints The `crypton-x509-validation` and `crypton-x509` libraries did not enforce the X.509 Name Constraints extension during certificate validation. The Name Constraints extension is a critical X.509 extension that restricts the namespace (permitted and excluded subtrees) for which a CA is authorized to issue certificates. Without this enforcement, a TLS client would accept certificates with Subject Alternative Names (SANs) that fall outside the issuing CA's permitted subtrees. An attacker with access to a name-constrained sub-CA's private key could therefore issue certificates for domains outside the sub-CA's intended scope, enabling impersonation of arbitrary domains and man-in-the-middle attacks on TLS connections. The older `x509` and `x509-validation` packages are also affected but are no longer maintained and have no fix available. This issue was fixed in `crypton-x509-validation-1.9.1` and `crypton-x509-1.9.1`.