CVE-2026-91768
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.
Predictions
Heuristic predictions, AS-IS, for prioritization only.
Mitigations
No mitigations published for this CVE yet.
The vendor-content worker queues fetches as references arrive (check back in a few minutes). Or — if you've already worked around this in production — publish your fix to the community-verified tier.
Propose a mitigation on Community Mitigations published via the community go through AI scoring + 2 human reviewers + 7-day silent objection window before landing here withsource_tier=community-verified.
OS impact
Debian Affected 4 releases
| Version | Status | Fixed in |
|---|---|---|
| trixie | Affected | — |
| sid | Affected | — |
| forky | Affected | — |
| bookworm | Affected | — |
Alpine Fixed 1 release
| Version | Status | Fixed in |
|---|---|---|
| v3.24 | Fixed | 8.3.35-r0 |
References
- https://security-tracker.debian.org/tracker/CVE-2026-91768
- https://security.alpinelinux.org/vuln/CVE-2026-91768
- https://pkgs.alpinelinux.org/packages?name=php83
- https://pkgs.alpinelinux.org/packages?name=php84
- https://pkgs.alpinelinux.org/packages?name=php85
- https://github.com/php/php-src/security/advisories/GHSA-62xp-839h-2637
CWEs
CWE-1023
Community-verified mitigations for this CVE will appear above when contributors publish them.
Verify integrity in audit chain (admin only). AS-IS.