CVE-2026-91768
IPv6 ACL bypass in FastCGI listen.allowed_clients due to partial address comparison (memcmp 12 bytes)
CVSS Score
6.5
EPSS Score
0.0%
EPSS Percentile
0th
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.
| CWE | CWE-1023 |
| Vendor | php group |
| Product | php |
| Published | Sep 25, 2026 |
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CVSS v3 Breakdown
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N Attack Vector
Adjacent
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
None
Affected Versions
PHP Group / PHP
8.2.* < 8.2.34 8.3.* < 8.3.35 8.4.* < 8.4.26 8.5.* < 8.5.11
References
Credits
🔍 @l8BL (GitHub) 🔍 @OSTIF-Derek (GitHub) 🔍 Ilia Alshanetsky Alexandre Daubois Arnaud Le Blanc Jakub Zelenka