A cross-site scripting (XSS) vulnerabilities was identified in October CMS backend configuration forms:
Customize Backend Styles permission could inject malicious HTML/JS into the stylesheet input atA specially crafted input could break out of the intended <style> context, allowing arbitrary script execution across backend pages for all users.
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.
If upgrading immediately is not possible:
- Restrict the permissions Customize Backend Styles to fully trusted administrators only.
This reduces exposure but does not fully eliminate risk.
{
"nvd_published_at": "2026-01-10T04:16:00Z",
"cwe_ids": [
"CWE-79"
],
"github_reviewed_at": "2026-01-09T20:12:24Z",
"severity": "MODERATE",
"github_reviewed": true
}