PHP OpenSSL Wildcard Name Verification Buffer Underflow
CVE-2026-91767 Published on September 25, 2026

Heap-buffer-overflow in php_openssl_matches_wildcard_name on crafted server cert wildcard CN
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.

Vendor Advisory NVD

Vulnerability Analysis

Attack Vector:
ADJACENT_NETWORK
Attack Complexity:
LOW
Privileges Required:
NONE
User Interaction:
NONE
Scope:
UNCHANGED
Confidentiality Impact:
HIGH
Integrity Impact:
NONE
Availability Impact:
NONE

Weakness Type

Heap-based Buffer Overflow

A heap overflow condition is a buffer overflow, where the buffer that can be overwritten is allocated in the heap portion of memory, generally meaning that the buffer was allocated using a routine such as malloc().


Products Associated with CVE-2026-91767

stack.watch emails you whenever new vulnerabilities are published in PHP or Php:php Php. Just hit a watch button to start following.

PHP
 
Php:php Php
 

Affected Versions

PHP Group PHP: