CVE-2026-91769
TLS Hostname Verification Falls Back to CN After SAN Mismatch
- Published
- Last modified
- Where the record stands: published, rejected by its publisher, or superseded by another id.What do these mean? →
- published
- Whether CISA lists it in its Known Exploited Vulnerabilities catalog: proof that attackers are using it.What do these mean? →
- Not listed in CISA KEV
- Fix
- Fixed in 8.2.34, 8.3.35, 8.4.26, 8.5.11
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
CISA's decision points: whether it is exploited, whether attacks can be automated, and how much control an attacker gets. Assessed (SSVC 2.0.3).What do these mean? →
- Exploitation: none
- Automatable: no
- Technical impact: partial
Summary
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.
Timeline
- CVE published
- CISA SSVC assessment
Exploitation: none · Automatable: no · Technical impact: partial
- Record last updated
Affected versions
- ext-openssl
From 8.2.* · fixed in 8.2.34; From 8.3.* · fixed in 8.3.35; From 8.4.* · fixed in 8.4.26; From 8.5.* · fixed in 8.5.11