XSS in Octobercms October
CVE-2026-25133
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.
Vulnerability class: XSS (Cross-Site Scripting)
EPSS: 0.002 (12.3th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 4.8 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:N.
Affected products
- Octobercms October — versions < 3.7.14, >= 4.0.0, < 4.1.10
Weakness classification (CWE)
References
- security-advisories@github.com (x_refsource_CONFIRM, Vendor Advisory)
Frequently asked questions
- What is CVE-2026-25133?
- CVE-2026-25133 is a medium-severity vulnerability in Octobercms October, classified under Cross-site Scripting. CVSS score: 4.8/10. Published 2026-04-14.
- How severe is CVE-2026-25133?
- Medium severity. CVSS v3 base score is 4.8 out of 10.