Vulnerability in PHP Group
CVE-2026-91768
The IPv6 branch of the FastCGI client access check compares only the first 12 bytes of a 16-byte IPv6 address, so listen.allowed_clients matches on a /96 prefix instead of the exact address. An attacker who can source an address sharing the first 96 bits with an allowed one passes the check and reaches the FastCGI endpoint.
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-62xp-839h-2637 (vendor-advisory)
Frequently asked questions
- What is CVE-2026-91768?
- CVE-2026-91768 is a medium-severity vulnerability in PHP Group, classified under CWE-1023. CVSS score: 6.5/10. Published 2026-09-25.
- How severe is CVE-2026-91768?
- Medium severity. CVSS v3 base score is 6.5 out of 10.