CVE-2026-91768
IPv6 ACL bypass in FastCGI listen.allowed_clients due to partial address comparison (memcmp 12 bytes)
- State
- Published
- Severity
- 6.5 Medium
- Published
- Sep 25, 2026
- Updated
- Sep 28, 2026
- Reserved
- Sep 15, 2026
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.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 3.1 | 6.5 Medium | CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N | php |
Weaknesses
Affected Products
| Product | Versions |
|---|---|
PHPPHP Group |
|
References
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