Low [CVE-2026-64846] Arbitrary file truncation via time-of-check/time-of-use race
This low-severity Red Hat Linux advisory covers CVE-2026-64846 affecting Confidential Compute Attestation, Logging Subsystem for Red Hat OpenShift, OpenShift Lightspeed.
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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.
A flaw was found in Nix. Red Hat severity: Low — CVSS 2.8 (CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:N/I:L/A:N).
Weakness: CWE-367.
Affected products named by the advisory: Confidential Compute Attestation; Logging Subsystem for Red Hat OpenShift; OpenShift Lightspeed; OpenShift Service Mesh 3; and 41 more.
- < 2.35.0
Official advisory · high-confidence parse· fetched 2 hours ago·verify at source
Mitigation checklist
- Mitigation for this issue is either not available or the currently available options don't meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability. For additional information, refer to the upstream advisory at https://github.com/NixOS/nix/security/advisories/GHSA-6h4g-g5j9-fm5f. As a workaround, ensure the recursive-nix experimental feature is not enabled in production environments.
Official advisory · high-confidence parse· fetched 2 hours ago·verify at source
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