Heap-based buffer overflow in PHP - CVE-2026-91767
Published: September 24, 2026
Vulnerability identifier: #VU151927
CSH Severity: Medium
CVSS v4: 7.1 [CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-91767
CWE-ID: CWE-122
Exploitation vector: Adjecent network
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to disclose sensitive information.
The vulnerability exists due to a heap-based buffer overflow in php_openssl_matches_wildcard_name() in ext/openssl/xp_ssl.c when verifying a TLS server certificate wildcard name against a shorter hostname. A remote attacker can present a crafted TLS server certificate with a wildcard common name to disclose sensitive information.
The crafted certificate must be trusted by the certificate authority in use or be presented by a server controlled by the attacker.
Affected software
PHP
How to mitigate CVE-2026-91767
Install security update from vendor's website.
PHP - addressed in versions 8.2.34, 8.3.35, 8.4.26, 8.5.11