October CMS has Stored XSS in Event Log Mail Preview

Exploitation

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

CVSS 4.0

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

EPSS

• CVE-2026-24907: 0.20% estimated exploitation activity in the next 30 days; percentile 9.70 (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 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 - 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-j4j5-9x6g-rgxc

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# Patch Next advisory brief: CVE-2026-24907

Advisory: October CMS has Stored XSS in Event Log Mail Preview
IDs: CVE-2026-24907, GHSA-j4j5-9x6g-rgxc
Record: https://patchnext.com/advisories/cve-2026-24907 (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 5.1)
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-j4j5-9x6g-rgxc (GitHub-reviewed advisory GHSA-j4j5-9x6g-rgxc lists affected ranges: Packagist october/system >=4.0.0 =0 <=3.7.13)

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