GHSA-wvpq-h33f-8rp6
MEDIUMOctober CMS Vulnerable to Stored XSS via Branding Styles
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
october/system🐘october/systemReal-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
A cross-site scripting (XSS) vulnerabilities was identified in October CMS backend configuration forms:
- Branding and Appearances Styles
A user with theCustomize Backend Stylespermission could inject malicious HTML/JS into the stylesheet input at
Settings → Branding & Appearance → Styles.
A specially crafted input could break out of the intended <style> context, allowing arbitrary script execution across backend pages for all users.
Impact
- Persistent XSS across the backend interface.
- Exploitable by lower-privileged accounts with the above permissions.
- Potential consequences include privilege escalation, session hijacking, and execution of unauthorized actions in victim sessions.
Patches
The vulnerability has been patched in v4.0.12 and v3.7.13.
Stylesheet inputs are now sanitized to prevent injection of arbitrary HTML/JS.
All users are strongly encouraged to upgrade to the latest patched version.
Workarounds
If upgrading immediately is not possible:
- Restrict the permissions
Customize Backend Stylesto fully trusted administrators only.
This reduces exposure but does not fully eliminate risk.
Credits
- Reported by Nakkouch Tarek
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | october/system | all versions | 3.7.13 |
| 🐘Packagist | october/system | ≥ 4.0.0&&< 4.0.12 | 4.0.12 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for october/system. 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 october/system to 3.7.13 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-wvpq-h33f-8rp6 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-wvpq-h33f-8rp6 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-wvpq-h33f-8rp6. 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-wvpq-h33f-8rp6 in your dependencies?
O3 detects GHSA-wvpq-h33f-8rp6 across Packagist dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.