CVE-2026-55960
HighCVSS 7.5Exploitation Probability (EPSS)
Low risk4th percentile - higher than 4% of all known CVEs
Summary
The vulnerability allows an un-negotiated Raw Public Key (RFC 7250) to be accepted in place of an X.509 certificate, bypassing chain validation. This only affects builds with Raw Public Key support (HAVE_RPK) enabled, which is disabled by default but included with --enable-all.
Risk Assessment
The risk involves potential impersonation of a server or client without proper authentication, leading to man-in-the-middle attacks and compromise of communication confidentiality.
Recommendation
It is recommended to update to a version containing the fix, which defaults the expected type to X.509 when no type was negotiated. In the meantime, disable Raw Public Key support (HAVE_RPK) in the build configuration.
Original NVD description (English source)
Un-negotiated Raw Public Key (RFC 7250) accepted in place of an X.509 certificate, bypassing chain validation. A raw public key has no chain, so ParseCertRelative() accepts it without performing any trust verification; it must therefore only be accepted when RPK was actually negotiated for that peer. The check now defaults the expected type to X.509 (per RFC 7250/8446) when no type was negotiated, comparing against the received server certificate type on the client and the selected client certificate type on the server, and rejects any mismatch, including an un-negotiated raw public key, with UNSUPPORTED_CERTIFICATE. Only affects builds with Raw Public Key support (HAVE_RPK) enabled - disabled by default in a standalone build, but included in --enable-all.