Build-output corruption via leaked writable file descriptor
Published Mar 11, 2024 · Updated Jun 27, 2025
TOCTOU race in affected Nix releases allows local users to alter fixed-output derivations through abstract Unix sockets. A Linux fixed-output derivation can pass a writable store-path file descriptor over an abstract-namespace Unix domain socket, retaining it after Nix validates and marks the path immutable. Exploitation requires an untrusted fixed-output build and a cooperating host process or derivation, enabling post-validation corruption of expected build output.
Summary
What happened
TOCTOU race in affected Nix releases allows local users to alter fixed-output derivations through abstract Unix sockets. A Linux fixed-output derivation can pass a writable store-path file descriptor over an abstract-namespace Unix domain socket, retaining it after Nix validates and marks the path immutable. Exploitation requires an untrusted fixed-output build and a cooperating host process or derivation, enabling post-validation corruption of expected build output.
The record
- CVE
- CVE-2024-27297
- Published
- Mar 11, 2024
- Updated
- Jun 27, 2025
- Vendor
- NixOS
- Product
- Nix
- Classifications
- CWE-367, T1195.001
- Attack vector
- local
- Privileges
- Unavailable
Timeline
How it unfolded
- Mar 11, 2024CVE publishedPublication date reported by the CVE source.
- Jun 27, 2025Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=>= 2.19.0, < 2.19.4
- Affected versionversion=>= 2.20.0, < 2.20.5
- Affected versionversion=>= 2.3.0, < 2.3.18
- Affected versionversion=>= 2.4.0, < 2.18.2
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- Nix ca-fd-leak regression testproof of concept · demonstrated
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
See the directory against your own environment.
Your stack
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