October CMS has Stored XSS in Backend Editor Markup Classes

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

5.3 · CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N · score source

EPSS

• CVE-2026-24906: 0.25% estimated exploitation activity in the next 30 days; percentile 16.73 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

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

Published by the source

14 Apr 2026, 20:02 UTC

Last modified by the source

24 Apr 2026, 21:06 UTC

Source last checked

26 Oct 2026, 14:39 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-6qmh-j78v-ffp7

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# Patch Next advisory brief: CVE-2026-24906

Advisory: October CMS has Stored XSS in Backend Editor Markup Classes
IDs: CVE-2026-24906, GHSA-6qmh-j78v-ffp7
Record: https://patchnext.com/advisories/cve-2026-24906 (revision 1, source checked 26 Oct 2026, 14:39 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.3)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: october/system 4.1.10, 3.7.14. A vendor fix does not mean a deployment is fixed.

## Affected components
- Packagist october/system: affected >= 4.0.0, <= 4.1.9; <= 3.7.13; fixed in 4.1.10, 3.7.14

## Suggested inspection (read-only)
- Packagist october/system: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on october/system.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-6qmh-j78v-ffp7 (GitHub-reviewed advisory GHSA-6qmh-j78v-ffp7 lists affected ranges: Packagist october/system >=4.0.0 =0 <=3.7.13)

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