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Medium

October CMS has Stored XSS in Event Log Mail Preview

  • Disclosed: 14.04.2026
  • Updated: 11.10.2026 10:22

A stored cross-site scripting (XSS) vulnerability was identified in the Event Log mail preview feature. When viewing logged mail messages, HTML content was rendered in an iframe without proper sandboxing, allowing JavaScript execution in the viewer's browser context.

Impact

  • Stored XSS via mail template content rendered in Event Log
  • Could allow privilege escalation if a superuser views a malicious log entry
  • Requires authenticated backend access with mail template editing permissions
  • Requires a superuser to view the specific Event Log entry to trigger

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 mail template editing permissions to fully trusted administrators only
  • Restrict Event Log viewing permissions to minimize exposure

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-j4j5-9x6g-rgxc - 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 Event Log Mail Preview this entry
    Medium · 5.4 CVE-2026-24907 >= 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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