Vulnerability in PHP
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 · last modified .
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
EPSS: 0.002 (5.1th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 5th percentile — 5.1% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.001 · newest: 0.002 · change: +0.000
Affected products
Weakness classification (CWE)
References
- github.com/php/php-src/security/advisories/GHSA-vvx9-73fr-5jjx (Exploit, vendor-advisory, Vendor Advisory)
Frequently asked questions
- What is CVE-2026-91769?
- CVE-2026-91769 is a medium-severity vulnerability in PHP, 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.