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CVE-2021-27851

5.5 · MEDIUM

A security vulnerability that can lead to local privilege escalation has been found in ’guix-daemon’.

Published Apr 26, 2021CWE-264EPSS 0.33%

Overview

CVE-2021-27851 is a medium-severity vulnerability. It was published on April 26, 2021 and has a CVSS 3.1 base score of 5.5 (MEDIUM).

This vulnerability has a CVSS 3.1 base score of 5.5, rated MEDIUM. It requires local or adjacent network access to exploit. Some level of privileges is required for exploitation.

Technical 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.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

Refbugs.gnu.org/47229Refguix.gnu.org/en/blog/2021/risk-of-local-privilege-escalation-via-guix-daemon/Refbugs.gnu.org/47229Refguix.gnu.org/en/blog/2021/risk-of-local-privilege-escalation-via-guix-daemon/

How CyberStrike helps

Frequently asked questions

What is CVE-2021-27851?

CVE-2021-27851 is a medium-severity vulnerability. It was published on April 26, 2021 and has a CVSS 3.1 base score of 5.5 (MEDIUM).

How severe is CVE-2021-27851?

This vulnerability has a CVSS 3.1 base score of 5.5, rated MEDIUM. It requires local or adjacent network access to exploit. Some level of privileges is required for exploitation.

How do I fix or remediate CVE-2021-27851?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2021-27851?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2021-27851 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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