CVE-2026-64846: Nixos Nix

Low severity, CVSS 2.8. EPSS: 0.1% chance of exploitation in the next 30 days.

Nix is a package manager for Linux and other Unix systems. Prior to 2.35.0, a malicious derivation executed with the recursive-nix experimental feature can exploit a time-of-check/time-of-use race involving final symlink handling in the LocalStore restore path. The race can cause writeFile to follow a substituted final symlink when opening a path with O_TRUNC instead of enforcing FinalSymlink::DontFollow, allowing the Nix process or nix-daemon to create or truncate an empty file outside the build sandbox with the daemon user's permissions. The primitive does not provide arbitrary-content writes and requires winning the race. This issue is fixed in version 2.35.0.

Affected products

• Nixos Nix: before 2.35.0 (fixed in 2.35.0)

Published 2026-08-20. Last modified 2026-09-18.