The Nix, Lix, and Guix package managers allow a bypass of build isolation in which a user can elevate their privileges to the build user account (e.g., nixbld or guixbuild). This affects Nix through 2.24.15, 2.26.4, 2.28.4, and 2.29.1; Lix through 2.91.2, 2.92.2, and 2.93.1; and Guix before 1.4.0-38.0e79d5b.
The product assigns the wrong ownership, or does not properly verify the ownership, of an object or resource.