CVE-2024-47174: medium-severity vulnerability in NixOS nix
Credential leak when credentials are used with `<nix/fetchurl.nix>`
Published
E-mail alert when it lands in KEV, gets a public PoC or its score goes up.
13Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 5.9epss 0.3%
Nix is a package manager for Linux and other Unix systems. Starting in version 1.11 and prior to versions 2.18.8 and 2.24.8, `<nix/fetchurl.nix>` did not verify TLS certificates on HTTPS connections. This could lead to connection details such as full URLs or credentials leaking in case of a man-in-the-middle (MITM) attack. `<nix/fetchurl.nix>` is also known as the builtin derivation builder `builtin:fetchurl`. It's not to be confused with the evaluation-time function `builtins.fetchurl`, which was not affected by this issue. A user may be affected by the risk of leaking credentials if they have a `netrc` file for authentication, or rely on derivations with `impureEnvVars` set to use credentials from the environment. In addition, the commonplace trust-on-first-use (TOFU) technique of updating dependencies by specifying an invalid hash and obtaining it from a remote store was also vulnerable to a MITM injecting arbitrary store objects. This also applied to the impure derivations experimental feature. Note that this may also happen when using Nixpkgs fetchers to obtain new hashes when not using the fake hash method, although that mechanism is not implemented in Nix itself but rather in Nixpkgs using a fixed-output derivation. The behavior was introduced in version 1.11 to make it consistent with the Nixpkgs `pkgs.fetchurl` and to make `<nix/fetchurl.nix>` work in the derivation builder sandbox, which back then did not have access to the CA bundles by default. Nowadays, CA bundles are bind-mounted on Linux. This issue has been fixed in Nix 2.18.8 and 2.24.8. As a workaround, implement (authenticated) fetching with `pkgs.fetchurl` from Nixpkgs, using `impureEnvVars` and `curlOpts` as needed.
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
Affected products
NixOS · nixRelated CVEs — NixOS nix
In the same product, most dangerous first.
CVE-2024-45593CRITICALNix affected by unsafe NAR unpackingEPSS 0.6%CVE-2024-27297MEDIUMNix Corruption of fixed-output derivationsEPSS 0.6%CVE-2026-39860CRITICALNix sandbox escape: file write via symlink at FOD `.tmp` copy destinationEPSS 0.2%CVE-2024-51481LOWNix allows macOS sandbox escape via built-in buildersEPSS 0.2%CVE-2025-53819HIGHNix's privilege dropping to build user broke for macOSEPSS 0.1%CVE-2024-38531LOWNix sandbox escapeEPSS 0.1%