MediumGHSA-6qmh-j78v-ffp7CVE-2026-24906

October CMS has Stored XSS in Backend Editor Markup Classes

Published 14 Apr 2026 · Updated 5 May 2026

Affected packages

october/systemComposer
Affected
>=4.0.0 <4.1.10
Fixed in
4.1.10
Update to the fixed version for your release line, for example:composer require october/system:^4.1.10
october/systemComposer
Affected
<3.7.14
Fixed in
3.7.14
Update to the fixed version for your release line, for example:composer require october/system:^3.7.14

Details

A stored cross-site scripting (XSS) vulnerability was identified in the Backend Editor Settings. The Markup Classes fields (used for paragraph styles, inline styles, table styles, etc.) did not sanitize input to valid CSS class name characters. Malicious values were rendered unsanitized in Froala editor dropdown menus, allowing JavaScript execution when any user opened a RichEditor.

Impact

  • Stored XSS via editor settings rendered in RichEditor dropdowns
  • Could allow privilege escalation if a superuser opens any RichEditor (e.g., editing a blog post)
  • Requires authenticated backend access with editor settings permissions
  • Triggers on routine content editing operations

Patches

The vulnerability has been patched in v3.7.14 and v4.1.10. All users are encouraged to upgrade to the latest patched version.

Workarounds

If upgrading immediately is not possible:

  • Restrict editor settings permissions to fully trusted administrators only

References

Is GHSA-6qmh-j78v-ffp7 in any of your client repos?

Checking one package by hand is fine. Checking it across forty client projects is not. NPMscan reads the lockfiles in every GitHub repo you pick, finds each project with an affected october/system, and gives you the command that fixes it.

Scan a project free, no signupOr connect GitHub to scan every repo

References

Advisory data from OSV.dev (opens OSV.dev in a new tab), refreshed daily.