Unknown · Guix-Daemon · CVE-2021-27851
Name of the Vulnerable Software and Affected Versions:
guix-daemon versions prior to v1.2.0-75109-g94f0312546
guix-daemon versions v0.11.0-3298-g2608e40988 and later
Description:
A security issue has been discovered that can lead to local privilege escalation. It affects multi-user setups where guix-daemon runs locally. The attack involves an unprivileged user creating a build process, making its build directory world-writable, and then creating a hardlink to a root-owned file, such as /etc/shadow, in that directory. If the build fails and the --keep-failed option is used, the daemon changes ownership of the build tree, including the hardlink, to the user, granting them write access to the target file.
Recommendations:
For versions prior to v1.2.0-75109-g94f0312546, update to a version that includes the fix for this issue.
For versions v0.11.0-3298-g2608e40988 and later, update to a version that includes the fix for this issue.
As a temporary workaround, consider restricting the use of the `guix build` command with the --keep-failed option to prevent potential exploitation.