CVE-2026-91769 — MEDIUM (4.3)

Vulnerability Description

PHP's OpenSSL stream peer verification checks the certificate's subjectAltName entries first and, whenever no entry matches, falls back to the Common Name. RFC 6125 requires the CN to be ignored once the certificate presents any service identity, so a certificate carrying a non-matching DNS SAN was still accepted when its CN matched the requested peer_name. A certificate trusted by the client for one name can therefore be used to impersonate another.

CVSS Score

4.3

MEDIUM

CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

Attack Vector

ADJACENT_NETWORK

Attack Complexity

LOW

Privileges Required

NONE

User Interaction

NONE

Scope

UNCHANGED

Confidentiality

LOW

Integrity

NONE

Availability

NONE

Related Weaknesses (CWE)

CWE-297

References

https://github.com/php/php-src/security/advisories/GHSA-vvx9-73fr-5jjx

FAQ

What is CVE-2026-91769?

CVE-2026-91769 is a vulnerability with a CVSS score of 4.3 (MEDIUM). PHP's OpenSSL stream peer verification checks the certificate's subjectAltName entries first and, whenever no entry matches, falls back to the Common Name. RFC 6125 requires the CN to be ignored once ...

How severe is CVE-2026-91769?

CVE-2026-91769 has been rated MEDIUM with a CVSS base score of 4.3/10. Review the CVSS metrics above for detailed severity breakdown.

Is there a patch for CVE-2026-91769?

Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.