SB2026101536 - Time-of-check Time-of-use (TOCTOU) Race Condition in nix

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Main Vulnerability Database SB2026101536

SB2026101536 - Time-of-check Time-of-use (TOCTOU) Race Condition in nix

Published: October 15, 2026

Security Bulletin ID SB2026101536
CSH Severity
Low
Patch available
YES
Number of vulnerabilities 1
Exploitation vector Local access
Highest impact Data manipulation

Breakdown by Severity

Low 100%
  • Low
  • Medium
  • High
  • Critical

Description

This security bulletin contains information about 1 vulnerability.


1) Time-of-check Time-of-use (TOCTOU) Race Condition (CVE-ID: CVE-2026-64846)

CWE-ID: CWE-367 - Time-of-check Time-of-use (TOCTOU) Race Condition

CVSSv4: 2 [CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N]


The vulnerability allows a local user to truncate arbitrary files or create empty files outside the build sandbox.

The vulnerability exists due to a time-of-check time-of-use (TOCTOU) race condition in the recursive-nix experimental feature when processing a malicious derivation. A local user can exploit the race condition through a malicious derivation to truncate arbitrary files or create empty files outside the build sandbox.

Exploitation requires the recursive-nix experimental feature to be enabled. File operations occur with the permissions of the user running the nix process or nix-daemon.


Remediation

Install update from vendor's website.

References