LowGHSA-jj38-h5w5-mvpfCVE-2026-27937

October CMS: Reflected XSS via DataTable Form Widget

Published 21 Apr 2026 · Updated 5 May 2026

Affected packages

october/systemComposer
Affected
<3.7.16
Fixed in
3.7.16
Update to the fixed version for your release line, for example:composer require october/system:^3.7.16
october/systemComposer
Affected
>=4.0.0
Fixed in
No fix released

Details

A reflected Cross-Site Scripting (XSS) vulnerability was identified in the backend DataTable widget where a query parameter was rendered without proper output escaping.

Impact

  • Reflected XSS only, no stored/persistent component
  • The backend URL prefix is customizable and must be known or guessed by the attacker
  • Requires an authenticated backend user to visit a crafted URL
  • No direct access is gained without social engineering

Patches

The vulnerability has been patched in v3.7.16 and v4.1.16. The affected parameter is now properly escaped. All users are encouraged to upgrade to the latest patched version.

Workarounds

  • Use a non-default backend URL prefix (recommended as standard practice)
  • Implement a Content Security Policy (CSP) for backend pages

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References

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