CVE-2026-91768
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.
- Published Sep 25, 2026
- CVSS 6.5 medium
- 0.6% chance of exploitation in the next 30 days (EPSS)
Affected software
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