Buffer overflow in PHP Group
CVE-2026-91767
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.
Vulnerability class: Buffer Overflow
Published .
CVSS v3 metric
CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N.
EPSS exploit prediction
No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.
Affected products
Weakness classification (CWE)
References
- github.com/php/php-src/security/advisories/GHSA-xr7j-rvgx-xq5p (vendor-advisory)
Frequently asked questions
- What is CVE-2026-91767?
- CVE-2026-91767 is a medium-severity vulnerability in PHP Group, classified under Heap-based Buffer Overflow. CVSS score: 6.5/10. Published 2026-09-25.
- How severe is CVE-2026-91767?
- Medium severity. CVSS v3 base score is 6.5 out of 10.