Description
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.
References3
Metrics
- CVSS 3.1
-
2.8
LOW
Score source: CNA
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:N/I:L/A:N - EPSS — exploit probability
- 0% percentile: 1 · as of 10 November 2026
- CWE
- CWE-61CWE-367
Could this be exploited in your environment?
A patch closes the known hole. A penetration test shows what an attacker can still reach — with proof.