CVE-2026-91767 Heap-buffer-overflow in php_openssl_matches_wildcard_name on crafted server cert wildcard CN

What is CVE-2026-91767?

CVE-2026-91767 is a medium-severity memory corruption 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_openssl_matches_wildcard_name() in ext/openssl/xp_ssl.c underflows the length argument passed to memchr() when a TLS server certificate presents a wildcard name whose literal characters are together longer than the hostname being verified. A malicious server presenting such a certificate makes the PHP client read up to SIZE_MAX bytes past the end of a heap allocation. The path is reachable from any default client stream, because verify_peer_name is enabled by default.

Weakness: CWE-122

Which versions are affected by CVE-2026-91767?

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-2026-91767?

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

Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.

Is CVE-2026-91767 being exploited?

There is no known exploitation of CVE-2026-91767 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-104922, BELL-CVE-2026-91767, BIT-libphp-2026-91767, BIT-php-2026-91767, BIT-php-min-2026-91767, CLEANSTART-2026-JC19240 and 11 more.