Path Traversal Vulnerability in `LESS` Parser allows reading of sensitive server files
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.
Affected software
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| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| Composer package | flarum/core | < 1.7.0 | 1.7.0 |
References
- https://github.com/flarum/framework/security/advisories/GHSA-vhm8-wwrf-3gcw
- https://nvd.nist.gov/vuln/detail/CVE-2023-27577
- https://github.com/flarum/framework/commit/1761660c98ea5a3e9665fb8e6041d1f2ee62a444
- https://github.com/flarum/flarum-core
- https://github.com/flarum/flarum-core/releases/tag/v1.7.0
- CVSS vector
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:H/A:H- Weakness (CWE)
CWE-22- Platform
- Composer
- Package
flarum/core- Disclosed
- 13.03.2023
- Updated
- 11.10.2026 10:22
Sources and licenses
OSV / GitHub Advisory Database - GHSA-vhm8-wwrf-3gcw - CC BY 4.0
Vulnerability history: flarum/core
All published vulnerabilities of this package (Composer package), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 9
- First → latest
- 06.2021 04.2026
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- Critical 2
- High 1
- Medium 5
- Low 1
Disclosures per year
- 2021: 1
- 2022: 1
- 2023: 4
- 2024: 1
- 2025: 1
- 2026: 1
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Path Traversal Vulnerability in `LESS` Parser allows reading of sensitive server files this entry
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