CVE-2026-91769TLS Hostname Verification Falls Back to CN After SAN Mismatch
Updated under an hour ago ()
Does this affect you?
It affects PHP Group PHP. Add what you run to find out whether that includes you.
No exploitation reported and no EPSS estimate yet.
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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
- 4.3 MEDIUM (v3.1, CNA)CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
- Weakness (CWE)
- CWE-297
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- php
- NVD analysis
- Awaiting Analysis
- Record last updated
- Oct 4, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
PHP Group PHP php_group:php (from the name) | from 8.2.* before 8.2.34; from 8.3.* before 8.3.35; from 8.4.* before 8.4.26; from 8.5.* before 8.5.11 | CNA record |
References
- https://github.com/php/php-src/security/advisories/GHSA-vvx9-73fr-5jjxvendor-advisory
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.