Hydra

Hydra is a Continuous Integration service for Nix based projects. It is possible to trigger evaluations in Hydra without any authentication. Depending on the size of evaluations, this can impact the availability of systems. The problem can be fixed by applying https://github.com/NixOS/hydra/commit/f73043378907c2c7e44f633ad764c8bdd1c947d5 to any Hydra package. Users are advised to upgrade. Users unable to upgrade should deny the `/api/push` route in a reverse proxy. This also breaks the "Evaluate jobset" button in the frontend.

Published: 2024-08-27T20:33:01.326Z
Updated: 2024-08-28T14:03:00.616Z

Hydra is a Continuous Integration service for Nix based projects. Attackers can execute arbitrary code in the browser context of Hydra and execute authenticated HTTP requests. The abused feature allows Nix builds to specify files that Hydra serves to clients. One use of this functionality is serving NixOS `.iso` files. The issue is only with html files served by Hydra. The issue has been patched on https://hydra.nixos.org around 2024-04-21 14:30 UTC. The nixpkgs package were fixed in unstable and 23.11. Users with custom Hydra packages can apply the fix commit to their local installations. The vulnerability is only triggered when opening HTML build artifacts, so not opening them until the vulnerability is fixed works around the issue.

Published: 2024-04-22T22:24:06.762Z
Updated: 2024-08-02T02:13:40.333Z