CVE-2026-91769 TLS Hostname Verification Falls Back to CN After SAN Mismatch

What is CVE-2026-91769?

CVE-2026-91769 is a medium-severity vulnerability in Php Php, published on 25 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

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.

Weakness: CWE-297

Which versions are affected by CVE-2026-91769?

3 open source packages ship an affected version, including libphp, php and php-min. It affects 1 product.

Products include Php Php.

How do I fix CVE-2026-91769?

Upgrade libphp to a fixed version for your release line: 8.2.34, 8.3.35, 8.4.26 or 8.5.11.

Is CVE-2026-91769 being exploited?

There is no known exploitation of CVE-2026-91769 in the wild and no public exploit code.

Other vulnerabilities in Php Php

• CVE-2012-2688 Integer overflow in n/a Critical 10.0
• CVE-2012-2376 Memory corruption in n/a Critical 10.0
• CVE-2011-3268 Memory corruption in n/a Critical 10.0
• CVE-2009-4143 Other in n/a Critical 10.0
• CVE-2008-5557 Memory corruption in n/a Critical 10.0

All Php Php vulnerabilities

Sources

• CVE record
• NVD
• OSV
• How this page is made

Also known as AZL-104907, BELL-CVE-2026-91769, BIT-libphp-2026-91769, BIT-php-2026-91769, BIT-php-min-2026-91769, CLEANSTART-2026-AU05968 and 11 more.