CVE-2026-91769
mediumpriority · track · 0EPSS 0.002 · 5 %ileDEUSEPSS · scored 2026-10-28
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
Technical severity, 0–10. One row per scoring source.
base score 0–10 · higher = more severe · hover a vector to decode
ssvc
A stakeholder decision — act, attend, or track — from exploitation and impact.
weaknesses
The CWE weakness classes this flaw belongs to.
affected products (28)
Products and version ranges known to be affected.
advisories (4)
Vendor and ecosystem advisories describing this.
- WID-SEC-W-2026-3585PHP: Mehrere SchwachstellenDeutsch2026-09-24csaf · cert_bundDE
Ein Angreifer kann mehrere Schwachstellen in PHP ausnutzen, um einen Denial of Service Angriff durchzuführen, um Informationen offenzulegen oder die Integrität zu verletzen.
- BIT-libphp-2026-91769TLS Hostname Verification Falls Back to CN After SAN Mismatch2026-10-01vendor · osvUS
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.
- BIT-php-2026-91769TLS Hostname Verification Falls Back to CN After SAN Mismatch2026-10-01vendor · osvUS
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.
- BIT-php-min-2026-91769TLS Hostname Verification Falls Back to CN After SAN Mismatch2026-10-01vendor · osvUS
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.
also known as (3)
Other names and identifiers for this entity.
sources
Which sources assert this record, and when.
references (1) nvd
External citations — patches, advisories, analysis.
- https://github.com/php/php-src/security/advisories/GHSA-vvx9-73fr-5jjxVendor AdvisoryExploit
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