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Medium

October CMS has Stored XSS in Backend Editor Markup Classes

  • Disclosed: 14.04.2026
  • Updated: 11.10.2026 10:22

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

Affected software

Click a technology to see all vulnerabilities affecting it.

PlatformPackageVulnerable versionsFixed in
Composer package october/system >= 4.0.0, < 4.1.10, < 3.7.14 4.1.10, 3.7.14

References

CVSS score 5.4/10
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
Weakness (CWE)
CWE-79
Platform
Composer
Package
october/system
Disclosed
14.04.2026
Updated
11.10.2026 10:22

Sources and licenses

OSV / GitHub Advisory Database - GHSA-6qmh-j78v-ffp7 - CC BY 4.0

Vulnerability history: october/system

All published vulnerabilities of this package (Composer package), newest first. Shows whether this is a one-off slip or a package that needs watching.

All (25) in the archive
Total entries
25
First → latest
06.2020 09.2026
Without a fix
0
Exploited in attacks
1

Severity breakdown

  • Critical 1
  • High 8
  • Medium 9
  • Low 7

Disclosures per year

Severity:
  1. October CMS has Stored XSS in Backend Editor Markup Classes this entry
    Medium · 5.4 CVE-2026-24906 >= 4.0.0, < 4.1.10, < 3.7.14 4.1.10, 3.7.14
  2. October CMS safe mode bypass using Twig sandbox escape
    Critical · 9.1 CVE-2023-44382 >= 3.0.0, < 3.4.15 3.4.15
  3. October CMS Safe Mode bypass leads to authenticated Remote Code Execution
    High · 7.2 CVE-2022-35944 >= 2.0.0, < 2.2.34, >= 3.0.0, < 3.0.66 2.2.34, 3.0.66
  4. October CMS upload process vulnerable to RCE via Race Condition
    High · 8.1 CVE-2022-24800 < 1.0.476, >= 1.1.0, < 1.1.12, >= 2.0.0, < 2.2.15 1.0.476, 1.1.12, 2.2.15
  5. Authenticated remote code execution in October CMS
    High · 7.2 CVE-2022-21705 < 1.0.474, >= 1.1.0, < 1.1.10, >= 2.0.0, < 2.1.27 1.0.474, 1.1.10, 2.1.27
  6. october/system arbitrary code execution
    High · 8.8 CVE-2021-32650 >= 1.1.0, < 1.1.6, < 1.0.473 1.1.6, 1.0.473
  7. October/System authenticated file write leads to remote code execution
    High · 8.8 CVE-2021-32649 >= 1.1.0, < 1.1.6, < 1.0.473 1.1.6, 1.0.473
  8. Deleted Admin Can Sign In to Admin Interface
    High · 7.2 CVE-2021-41126 >= 2.1.0, < 2.1.12 2.1.12
  9. October CMS auth bypass and account takeover
    High · 7.4 CVE-2021-29487 < 1.0.472, >= 1.1.1, < 1.1.5 1.0.472, 1.1.5
  10. Account Takeover in Octobercms
    High · 8.2 Exploited in attacks CVE-2021-32648 < 1.0.472, >= 1.1.1, < 1.1.5 1.0.472, 1.1.5

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