CVE-2021-27851

Severity CVSS v4.0:

Pending analysis

Type:

CWE-59 Link Following

Publication date:

26/04/2021

Last modified:

29/07/2022

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.

Impact

Vector 3.x

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N CVSS v3.1 Severity and Metrics:

Base Score: 5.50 MEDIUM
Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N

Attack Vector (AV): Local
Attack Complexity (AC): Low
Privileges Required (PR): Low
User Interaction (UI): None
Scope (S): Unchanged
Confidentiality (C): None
Integrity (I): High
Availability (A): None

Base Score 3.x

5.50

Severity 3.x

MEDIUM

Vector 2.0

AV:L/AC:L/Au:N/C:N/I:P/A:N CVSS v2.0 Severity and Metrics:

Base Score: 2.10 LOW
Vector: AV:L/AC:L/Au:N/C:N/I:P/A:N

Attack Vector (AV): Local
Attack Complexity (AC): Low
Authentication (Au): None
Confidentiality (C): None
Integrity (I): Physical
Availability (A): None