CVE-2026-91768 — IPv6 ACL bypass in FastCGI listen.allowed_clients due to partial address comparison (memcmp 12 bytes)

CVE-2026-91768

IPv6 ACL bypass in FastCGI listen.allowed_clients due to partial address comparison (memcmp 12 bytes) PUBLISHED

Description (CNA)

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.

Affected (CNA)

Vendor / product	Versions
PHP Group / PHP	affected 8.2.* before 8.2.34; affected 8.3.* before 8.3.35; affected 8.4.* before 8.4.26; affected 8.5.* before 8.5.11

CWE

CWE-1023

References

https://github.com/php/php-src/security/advisories/GHSA-62xp-839h-2637

ADP enrichment

CISA-ADP

No English description supplied.

No references supplied.