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CVE record · CVE-2026-39860

Nix sandbox escape: file write via symlink at FOD `.tmp` copy destination

CVSS 9.0 CriticalCriticalEPSS 0.0020 · 9th percentile

Critical, because:

  • CVSS score 9.0: 9.0 or more.

How we decide what’s critical

Published by the CVE Program (CNA: GitHub_M) at 8 Apr 2026, 20:58 UTC. agentprime has not analysed this yet, so whether it affects any app is not known. This CVE names a vendor and product rather than a package, so the lockfile check doesn’t match it.

Affected products, as the CNA wrote them
VendorProductVersions
NixOS nix
  • affected >= 2.21, < 2.28.6
  • affected >= 2.29.0, < 2.29.3
  • affected >= 2.30.0, < 2.30.4
  • affected >= 2.31.0, < 2.31.4
  • affected >= 2.32.0, < 2.32.7
  • affected >= 2.33.0, < 2.33.4
  • affected >= 2.34.0, < 2.34.5
  • affected >= 2.20.5, <= 2.20.9
  • affected >= 2.19.4, <= 2.19.7
  • affected >= 2.18.2, <= 2.18.9
Identifiers
CVE-2026-39860
CNA
GitHub_M
Weakness (CWE)
CWE-61
Tags
Published
8 Apr 2026
Updated
9 Apr 2026

Not analysed yet

We haven’t published our own analysis of this CVE. If a person reviews it, this page will say what’s affected and what has to be true for it to matter.

Severity and exploitation

ScoreRatingCVSSVectorSource
9.0 Critical 3.1 CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N CNA (GitHub_M)
  • CISA KEV Not listed.
  • EPSS 0.0020, the 9th percentile, on 6 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

This record came from the full history of the CVE Program, published 8 Apr 2026. New records show when each source confirmed them.

Sources

References from the CNA

Facts on this page come from the CVE List as the CNA published them, with CVSS from the sources named above, CISA KEV and FIRST EPSS. Vendors, products and versions are shown as the CNA wrote them. We don’t reproduce the CVE’s description.