GHSA-vhm8-wwrf-3gcw
MEDIUMPath Traversal Vulnerability in `LESS` Parser allows reading of sensitive server files
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
Blast Radius
flarum/coreReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Packagist packages — download data is not available via public APIs for these ecosystems.
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.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | flarum/core | all versions | 1.7.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for flarum/core. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update flarum/core to 1.7.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-vhm8-wwrf-3gcw is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether GHSA-vhm8-wwrf-3gcw is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to GHSA-vhm8-wwrf-3gcw. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-vhm8-wwrf-3gcw in your dependencies?
O3 detects GHSA-vhm8-wwrf-3gcw across Packagist dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.