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Path Traversal Vulnerability in `LESS` Parser allows reading of sensitive server files

Moderate
SychO9 published GHSA-vhm8-wwrf-3gcw Mar 10, 2023

Package

composer flarum/core (Composer)

Affected versions

< 1.6.3

Patched versions

1.7.0

Description

Impact

If an admin account has already been compromised by an attacker, the LESS parser can be exploited to read sensitive files on the server through the use of path traversal techniques.

An attacker can achieve this by providing an absolute path to a sensitive file in the custom LESS setting, which the LESS parser will then read. For example, an attacker could use the following code to read the contents of the /etc/passwd file:

@import (inline) '/etc/passwd';

.test {
  content: data-uri('/etc/passwd');
}

Patches

The vulnerability has been addressed in version 1.7. Users should upgrade to this version to mitigate the vulnerability.

Workarounds

Users can mitigate the vulnerability by ensuring that their admin accounts are secured with strong passwords and other best practices for account security. Additionally, users can limit the exposure of sensitive files on the server by implementing appropriate file permissions and access controls.

Severity

Moderate

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
High
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
High
Availability
High

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:H/A:H

CVE ID

CVE-2023-27577

Weaknesses