CVE-2026-25133 October CMS has Stored XSS via SVG Filter Bypass
Authenticated attackers can upload malicious SVG files to trigger stored XSS, potentially leading to privilege escalation when viewed by superusers.
- Exploited in the wild
- Not known
- Login needed
- An administrator
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2026-25133?
CVE-2026-25133 is a medium-severity cross-site scripting vulnerability in Octobercms October, published on 14 Apr 2026. An attacker needs administrator access to exploit it, and only if a user opens a file or follows a link.
Official 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 SVG sanitization logic. The regex pattern used to strip event handler attributes (such as onclick or onload) could be bypassed using a crafted payload that exploits how the pattern matches attribute boundaries, allowing malicious SVG files to be uploaded through the Media Manager with embedded JavaScript. Exploitation could lead to privilege escalation if a superuser views or embeds the malicious SVG, and requires authenticated backend access with media upload permissions. The SVG must be viewed or embedded in a page for the payload to trigger. This issue has been fixed in versions 3.7.14 and 4.1.10.
Weakness: CWE-79
Which versions are affected by CVE-2026-25133?
4 open source packages ship an affected version, including october/rain. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
october/rain Packagist | All versions | 3.7.14 |
october/rain Packagist | All versions | 3.7.14 |
october/rain Packagist | From 4.0.0 | 4.1.10 |
october/rain Packagist | From 4.0.0 | 4.1.10 |
Products include Octobercms October.
How do I fix CVE-2026-25133?
Upgrade october/rain to a fixed version for your release line: 3.7.14 or 4.1.10.
Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.
Is CVE-2026-25133 being exploited?
There is no known exploitation of CVE-2026-25133 in the wild and no public exploit code.
Other vulnerabilities in Octobercms October
Sources
Also known as GHSA-gcqv-f29m-67gr.