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.
Metrics
Affected Vendors & Products
Advisories
| Source | ID | Title |
|---|---|---|
Debian DSA |
DSA-6514-1 | php8.4 security update |
Fixes
Solution
No solution given by the vendor.
Workaround
No workaround given by the vendor.
References
History
Sat, 26 Sep 2026 00:15:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Weaknesses | CWE-940 | |
| References |
| |
| Metrics |
threat_severity
|
threat_severity
|
Fri, 25 Sep 2026 21:30:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| 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. | |
| Title | IPv6 ACL bypass in FastCGI listen.allowed_clients due to partial address comparison (memcmp 12 bytes) | |
| Weaknesses | CWE-1023 | |
| References |
| |
| Metrics |
cvssV3_1
|
Projects
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Status: PUBLISHED
Assigner: php
Published:
Updated: 2026-09-25T21:07:30.950Z
Reserved: 2026-09-15T00:42:30.045Z
Link: CVE-2026-91768
No data.
Status : Received
Published: 2026-09-25T22:18:49.807
Modified: 2026-09-25T22:18:49.807
Link: CVE-2026-91768
OpenCVE Enrichment
Updated: 2026-09-25T23:30:17Z
Debian DSA