Vulnerability · Published Apr 26, 2021 · Assigned by certcc
CVE-2021-27851Local privilege escalation in GNU Guix via guix-daemon and '--keep-failed'
Medium 5.5
In plain English
A medium-severity security flaw in guix-daemon from GNU Guix. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 27% of all known vulnerabilities).
Official description
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.
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| GNU Guix | guix-daemon | v0.11.0-3298-g2608e40988 – before unspecifiedunspecified – before v1.2.0-75109-g94f0312546 |
Weakness: CWE-264
References
- https://guix.gnu.org/en/blog/2021/risk-of-local-privilege-escalation-via-guix-daemon/ x_refsource_MISC
- https://bugs.gnu.org/47229 x_refsource_MISC