CVE-2026-39860

HIGH EPSS 9.2%
Published Apr 8, 20262mo ago · Modified Jun 17, 20261w ago
8.4 CVSS 3.1
High
Find Similar
Published Apr 8, 2026 2mo ago
Last Modified Jun 17, 2026 1w ago

Description

Nix is a package manager for Linux and other Unix systems. A bug in the fix for CVE-2024-27297 allowed for arbitrary overwrites of files writable by the Nix process orchestrating the builds (typically the Nix daemon running as root in multi-user installations) by following symlinks during fixed-output derivation output registration. This affects sandboxed Linux builds - sandboxed macOS builds are unaffected. The location of the temporary output used for the output copy was located inside the build chroot. A symlink, pointing to an arbitrary location in the filesystem, could be created by the derivation builder at that path. During output registration, the Nix process (running in the host mount namespace) would follow that symlink and overwrite the destination with the derivation's output contents. In multi-user installations, this allows all users able to submit builds to the Nix daemon (allowed-users - defaulting to all users) to gain root privileges by modifying sensitive files. This vulnerability is fixed in 2.34.5, 2.33.4, 2.32.7, 2.31.4, 2.30.4, 2.29.3, and 2.28.6.

CVSS Details

Base Score
8.4
Exploitability
2.0
Impact
5.8
Vector string
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N
Attack Vector Local
Attack Complexity Low
Privileges Required Low
User Interaction None
Scope Changed
Confidentiality High
Integrity High
Availability None

Threat Intelligence

EPSS Exploit Probability
9.2% percentile
Exploit & Patch Status
No Known Exploit
Patch Available

Weaknesses 1

CWE-61

Affected Products 11

VendorProductVersionRange
nixosnix*≥2.18.2  –  ≤2.18.9
nixosnix*≥2.19.4  –  ≤2.19.7
nixosnix*≥2.20.5  –  ≤2.20.9
nixosnix*≥2.21.0  –  <2.28.6
nixosnix*≥2.29.0  –  <2.29.3
nixosnix*≥2.30.0  –  <2.30.4
nixosnix*≥2.31.0  –  <2.31.4
nixosnix*≥2.32.0  –  <2.32.7
nixosnix*≥2.33.0  –  <2.33.4
nixosnix*≥2.34.0  –  <2.34.5
linuxlinux_kernel*any

References 6

  • github.com https://github.com/NixOS/nix/commit/244f3eee0bbc7f11e9b383a15ed7368e2c4becc9
    Patch
  • github.com https://github.com/NixOS/nix/commit/4bc5a3510fa3735798f9ed3a2a30a3ea7b32343a
    Patch
  • github.com https://github.com/NixOS/nix/commit/7794354a982449927ee7401cdeb573ddd16c4688
    Patch
  • github.com https://github.com/NixOS/nix/commit/a3163b9eabb952b4aa96e376dea95ebcca97b31a
    Patch
  • github.com https://github.com/NixOS/nix/pull/10178
    Issue TrackingPatch
  • github.com https://github.com/NixOS/nix/security/advisories/GHSA-g3g9-5vj6-r3gj
    MitigationPatchVendor Advisory

Remediation

  • github.com https://github.com/NixOS/nix/commit/244f3eee0bbc7f11e9b383a15ed7368e2c4becc9
    Patch
  • github.com https://github.com/NixOS/nix/commit/4bc5a3510fa3735798f9ed3a2a30a3ea7b32343a
    Patch
  • github.com https://github.com/NixOS/nix/commit/7794354a982449927ee7401cdeb573ddd16c4688
    Patch
  • github.com https://github.com/NixOS/nix/commit/a3163b9eabb952b4aa96e376dea95ebcca97b31a
    Patch
  • github.com https://github.com/NixOS/nix/pull/10178
    Issue TrackingPatch
  • github.com https://github.com/NixOS/nix/security/advisories/GHSA-g3g9-5vj6-r3gj
    MitigationPatchVendor Advisory