CVE-2026-24906: October CMS has Stored XSS in its Backend Editor Markup Classes
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 - Reported by Chris Alupului
Other sources
October is a Content Management System (CMS) and web platform. Versions prior to 3.7.14 and 4.1.10 contain a Stored Cross-Site Scripting (XSS) vulnerability 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. Exploitation could lead to privilege escalation if a superuser opens any RichEditor during routine content editing (e.g., editing a blog post), and requires authenticated backend access with editor settings permissions. This issue has been fixed in versions 3.7.14 and 4.1.10. To workaround this issue, restrict editor settings permissions to fully trusted administrators only
— MITRE
Affected Software
Event History
Frequently Asked Questions
What is the severity of CVE-2026-24906?
CVE-2026-24906 is considered a high-severity vulnerability due to the potential for stored cross-site scripting attacks.
How do I fix CVE-2026-24906?
To fix CVE-2026-24906, upgrade October CMS to version 3.7.14 or 4.1.10 or later.
What versions of October CMS are affected by CVE-2026-24906?
CVE-2026-24906 affects October CMS versions prior to 3.7.14 and 4.1.10.
What type of vulnerability is CVE-2026-24906?
CVE-2026-24906 is a stored cross-site scripting (XSS) vulnerability.
Where can I find more information about CVE-2026-24906?
More information on CVE-2026-24906 can typically be found in security advisories from the October CMS project.