Title: Nix de NixOS, Description: Nix es un gestor de paquetes para Linux y otros sistemas Unix. Un error en la corrección para CVE-2024-27299 permitió sobrescrituras arbitrarias de archivos escribibles por el proceso Nix que orquesta las compilaciones (típicamente el demonio Nix ejecutándose como root en instalaciones multiusuario) al seguir enlaces simbólicos durante el registro de salida de derivaciones de salida fija. Esto afecta a las compilaciones de Linux en entornos aislados; las compilaciones de macOS en entornos aislados no se ven afectadas. La ubicación de la salida temporal utilizada para la copia de salida se encontraba dentro del chroot de compilación. Un enlace simbólico, apuntando a una ubicación arbitraria en el sistema de archivos, podría ser creado por el constructor de la derivación en esa ruta. Durante el registro de salida, el proceso Nix (ejecutándose en el espacio de nombres de montaje del host) seguiría ese enlace simbólico y sobrescribiría el destino con el contenido de salida de la derivación. En instalaciones multiusuario, esto permite a todos los usuarios capaces de enviar compilaciones al demonio Nix (usuarios permitidos - por defecto todos los usuarios) obtener privilegios de root modificando archivos sensibles. Esta vulnerabilidad está corregida en 2.34.5, 2.33.4, 2.32.7, 2.31.4, 2.30.4, 2.29.3 y 2.28.6.

{"timestamp":"2026-04-09T13:42:26.389636Z","id":"CVE-2026-39860","options":[{"exploitation":"none"},{"automatable":"no"},{"technicalImpact":"total"}],"role":"CISA Coordinator","version":"2.0.3"}

[{"vendor":"NixOS","product":"nix","versions":[{"version":">= 2.21, < 2.28.6","status":"affected"},{"version":">= 2.29.0, < 2.29.3","status":"affected"},{"version":">= 2.30.0, < 2.30.4","status":"affected"},{"version":">= 2.31.0, < 2.31.4","status":"affected"},{"version":">= 2.32.0, < 2.32.7","status":"affected"},{"version":">= 2.33.0, < 2.33.4","status":"affected"},{"version":">= 2.34.0, < 2.34.5","status":"affected"},{"version":">= 2.20.5, <= 2.20.9","status":"affected"},{"version":">= 2.19.4, <= 2.19.7","status":"affected"},{"version":">= 2.18.2, <= 2.18.9","status":"affected"}]}]

AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N

AND
     OR
          *cpe:2.3:a:nixos:nix:*:*:*:*:*:*:*:* versions from (including) 2.18.2 up to (including) 2.18.9
          *cpe:2.3:a:nixos:nix:*:*:*:*:*:*:*:* versions from (including) 2.19.4 up to (including) 2.19.7
          *cpe:2.3:a:nixos:nix:*:*:*:*:*:*:*:* versions from (including) 2.20.5 up to (including) 2.20.9
          *cpe:2.3:a:nixos:nix:*:*:*:*:*:*:*:* versions from (including) 2.21.0 up to (excluding) 2.28.6
          *cpe:2.3:a:nixos:nix:*:*:*:*:*:*:*:* versions from (including) 2.29.0 up to (excluding) 2.29.3
          *cpe:2.3:a:nixos:nix:*:*:*:*:*:*:*:* versions from (including) 2.30.0 up to (excluding) 2.30.4
          *cpe:2.3:a:nixos:nix:*:*:*:*:*:*:*:* versions from (including) 2.31.0 up to (excluding) 2.31.4
          *cpe:2.3:a:nixos:nix:*:*:*:*:*:*:*:* versions from (including) 2.32.0 up to (excluding) 2.32.7
          *cpe:2.3:a:nixos:nix:*:*:*:*:*:*:*:* versions from (including) 2.33.0 up to (excluding) 2.33.4
          *cpe:2.3:a:nixos:nix:*:*:*:*:*:*:*:* versions from (including) 2.34.0 up to (excluding) 2.34.5
     OR
          cpe:2.3:o:linux:linux_kernel:-:*:*:*:*:*:*:*

GitHub, Inc.: https://github.com/NixOS/nix/commit/244f3eee0bbc7f11e9b383a15ed7368e2c4becc9 Types: Patch

GitHub, Inc.: https://github.com/NixOS/nix/commit/4bc5a3510fa3735798f9ed3a2a30a3ea7b32343a Types: Patch

GitHub, Inc.: https://github.com/NixOS/nix/commit/7794354a982449927ee7401cdeb573ddd16c4688 Types: Patch

GitHub, Inc.: https://github.com/NixOS/nix/commit/a3163b9eabb952b4aa96e376dea95ebcca97b31a Types: Patch

GitHub, Inc.: https://github.com/NixOS/nix/pull/10178 Types: Issue Tracking, Patch

GitHub, Inc.: https://github.com/NixOS/nix/security/advisories/GHSA-g3g9-5vj6-r3gj Types: Mitigation, Patch, Vendor Advisory

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.

AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N

CWE-61

https://github.com/NixOS/nix/commit/244f3eee0bbc7f11e9b383a15ed7368e2c4becc9

https://github.com/NixOS/nix/commit/4bc5a3510fa3735798f9ed3a2a30a3ea7b32343a

https://github.com/NixOS/nix/commit/7794354a982449927ee7401cdeb573ddd16c4688

https://github.com/NixOS/nix/commit/a3163b9eabb952b4aa96e376dea95ebcca97b31a

https://github.com/NixOS/nix/pull/10178

https://github.com/NixOS/nix/security/advisories/GHSA-g3g9-5vj6-r3gj