CVE-2026-39860
April 8, 2026, 9:26 p.m.
9.0
Critical
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.
Product(s) Impacted
| Vendor | Product | Versions |
|---|---|---|
| Nixos |
|
|
Weaknesses
Common security weaknesses mapped to this vulnerability.
CWE-61
UNIX Symbolic Link (Symlink) Following
The product, when opening a file or directory, does not sufficiently account for when the file is a symbolic link that resolves to a target outside of the intended control sphere. This could allow an attacker to cause the product to operate on unauthorized files.
*CPE(s)
Affected systems and software identified for this CVE.
| Type | Vendor | Product | Version | Update | Edition | Language | Software Edition | Target Software | Target Hardware | Other Information |
|---|---|---|---|---|---|---|---|---|---|---|
| a | nixos | nix | 2.34.5 | / | / | / | / | / | / | / |
| a | nixos | nix | 2.33.4 | / | / | / | / | / | / | / |
| a | nixos | nix | 2.32.7 | / | / | / | / | / | / | / |
| a | nixos | nix | 2.31.4 | / | / | / | / | / | / | / |
| a | nixos | nix | 2.30.4 | / | / | / | / | / | / | / |
| a | nixos | nix | 2.29.3 | / | / | / | / | / | / | / |
| a | nixos | nix | 2.28.6 | / | / | / | / | / | / | / |
References
Tags
CVSS Score
CVSS Data - 3.1
- Attack Vector: LOCAL
- Attack Complexity: LOW
- Privileges Required: NONE
- Scope: CHANGED
- Confidentiality Impact: HIGH
- Integrity Impact: HIGH
- Availability Impact: NONE
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N
Timeline
Published: April 8, 2026, 9:17 p.m.
Last Modified: April 8, 2026, 9:26 p.m.
Last Modified: April 8, 2026, 9:26 p.m.
Status : Undergoing Analysis
CVE has been marked for Analysis. Normally once in this state the CVE will be analyzed by NVD staff within 24 hours.
More infoSource
*Disclaimer: Some vulnerabilities do not have an associated CPE. To enhance the data, we use AI to infer CPEs based on CVE details. This is an automated process and might not always be accurate.