Vulnerability in PHP Group
CVE-2026-91769
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.
Published .
CVSS v3 metric
CVSS v3 base score 4.3 (Medium). Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N.
EPSS exploit prediction
No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.
Affected products
Weakness classification (CWE)
References
- github.com/php/php-src/security/advisories/GHSA-vvx9-73fr-5jjx (vendor-advisory)
Frequently asked questions
- What is CVE-2026-91769?
- CVE-2026-91769 is a medium-severity vulnerability in PHP Group, classified under Improper Validation of Certificate with Host Mismatch. CVSS score: 4.3/10. Published 2026-09-25.
- How severe is CVE-2026-91769?
- Medium severity. CVSS v3 base score is 4.3 out of 10.