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CVE-2021-27851


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.


Security Impact Summary

This vulnerability carries a MEDIUM severity rating with a CVSS v3.1 score of 5.5, requiring local system access to exploit with relatively low complexity without requiring user interaction requiring only low-level privileges . The vulnerability impacts integrity (unauthorized modifications), for affected systems. Impacting 1 product from gnu organizations running these solutions should prioritize assessment and patching.

Historical Context

Reported in 2021, this vulnerability emerged during an era marked by increased sophistication in supply chain attacks, cloud infrastructure vulnerabilities, and software-as-a-service (SaaS) security challenges. Security practices during this period emphasized zero-trust architectures, container security, and API protection.


Published

2021-04-26T16:15:07.433

Last Modified

2024-11-21T05:58:38.123

Status

Modified

Source

[email protected]

Severity

CVSSv3.1: 5.5 (MEDIUM)

CVSSv2 Vector

AV:L/AC:L/Au:N/C:N/I:P/A:N

  • Access Vector: LOCAL
  • Access Complexity: LOW
  • Authentication: NONE
  • Confidentiality Impact: NONE
  • Integrity Impact: PARTIAL
  • Availability Impact: NONE
Exploitability Score

3.9

Impact Score

2.9

Weaknesses
  • Type: Secondary
    CWE-264
  • Type: Primary
    CWE-59

Affected Vendors & Products
Type Vendor Product Version/Range Vulnerable?
Application gnu guix < 1.2.0 Yes

References

How SecUtils Interprets This CVE

SecUtils normalizes and enriches National Vulnerability Database (NVD) records by standardizing vendor and product identifiers, aggregating vulnerability metadata from both NVD and MITRE sources, and providing structured context for security teams. For gnu's affected products, we extract Common Platform Enumeration (CPE) data, Common Weakness Enumeration (CWE) classifications, CVSS severity metrics, and reference data to enable rapid vulnerability prioritization and asset correlation. This record contains no exploit code, proof-of-concept instructions, or attack methodologies—only defensive intelligence necessary for patch management, risk assessment, and security operations.