FormCms avatar upload feature has a stored cross-site scripting (XSS) vulnerability
Date: 2025-08
Affected: nuget/FormCMS
Attack vector: xss
Category: vulnerability-disclosure
Severity: Medium
CVE: CVE-2025-56236
CWE: CWE-434
CWE-79

FormCms v0.5.5 contains a stored cross-site scripting (XSS) vulnerability in the avatar upload feature. Authenticated users can upload .html files containing malicious JavaScript, which are accessible via a public URL. When a privileged user accesses the file, the script executes in their browser context.


Mitigations:

Architectural layers (MAESTRO):