IPv6 ACL bypass in FastCGI listen.allowed_clients due to partial address comparison (memcmp 12 bytes)
En bref
Sévérité
MEDIUM 6.5
EPSS
EPSS 0.38 % · centile 31 (2026-10-27)
État
PUBLISHED
Publiée
Mise à jour
Attribuée par
php
Statut NVD
Analyzed
Description
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.
