guix-daemon in GNU Guix before 5ab3c4c allows privilege escalation because build outputs are accessible by local users before file metadata concerns (e.g., for setuid and setgid programs) are properly addressed. The vulnerability can be remediated within the product via certain pull, reconfigure, and restart actions. Both 5ab3c4c and 5582241 are needed to resolve the vulnerability.

A race condition in the Nix, Lix, and Guix package managers enables changing the ownership of arbitrary files to the UID and GID of the build user (e.g., nixbld* or guixbuild*). This affects Nix before 2.24.15, 2.26.4, 2.28.4, and 2.29.1; Lix before 2.91.2, 2.92.2, and 2.93.1; and Guix before 1.4.0-38.0e79d5b.

In guix-daemon in GNU Guix before 1618ca7, a content-addressed-mirrors file can be written to create a setuid program that allows a regular user to gain the privileges of the build user that runs it (even after the build has ended).

Local privilege escalation in GNU Guix via guix-daemon and '--keep-failed'

A security vulnerability that can lead to local privilege escalation has been found in ’guix-daemon’. It affects multi-user setups in which ’guix-daemon’ runs locally. The attack consists in having an unprivileged user spawn a build process, for instance with `guix build`, that makes its build directory world-writable. The user then creates a hardlink to a root-owned file such as /etc/shadow in that build directory. If the user passed the --keep-failed option and the build eventually fails, the daemon changes ownership of the whole build tree, including the hardlink, to the user. At that point, the user has write access to the target file. Versions after and including v0.11.0-3298-g2608e40988, and versions prior to v1.2.0-75109-g94f0312546 are vulnerable.

GNU Guix 1.0.1 allows local users to gain access to an arbitrary user's account because the parent directory of the user-profile directories is world writable, a similar issue to CVE-2019-17365.

GuixSD prior to Git commit 5e66574a128937e7f2fcf146d146225703ccfd5d used POSIX hard links incorrectly, leading the creation of setuid executables in "the store", violating a fundamental security assumption of GNU Guix.