CVE-2026-25133 MEDIUM

CVE-2026-25133: October CMS has Stored XSS via SVG Filter Bypass

Vendor Octobercms
Product october
Weakness CWE-79 · XSS
Published April 14, 2026
Last update April 16, 2026

CVSS base score

4.8/10
Attack vector Network
Attack complexity Low
Privileges required High
User interaction
Confidentiality
Integrity

CVSS vector

CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:P/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N

What the vulnerability does

01Description

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.

Key dates

02Disclosure timeline

April 14, 2026 CVE published
April 16, 2026 Record updated