CVE-2026-64846
LowCVSS 2.8Exploitation Probability (EPSS)
Low risk0th percentile - higher than 0% of all known CVEs
Summary
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.
Risk Assessment
The risk includes the possibility of manipulating files outside the build sandbox, potentially leading to system integrity compromise or privilege escalation in the Nix environment.
Recommendation
It is recommended to upgrade Nix to version 2.35.0 or later and avoid using the experimental recursive-nix feature in production environments.
Other vulnerabilities in Nix
Original NVD description (English source)
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.