Unknown · Flask-Multipass · CVE-2026-25739
**Name of the Vulnerable Software and Affected Versions**
Indico versions prior to 3.3.10
**Description**
Indico, an event management system, is susceptible to a cross-site scripting issue when specific file types are uploaded as materials. The issue exists due to a flaw in the handling of file uploads. The system uses Flask-Multipass, a multi-backend authentication system for Flask. There is no information about the number of potentially affected devices worldwide or any real-world incidents where this issue was exploited. The vulnerable component is related to material upload functionality.
**Recommendations**
Upgrade to version 3.3.10 to resolve the issue.
If using nginx with Indico's `STATIC FILE METHOD` set to `xaccelredirect`, update the webserver configuration to include the following line in the `.xsf/indico/` location block: `add header Content-Security-Policy $upstream http content security policy;`.
As a workaround, apply a strict Content Security Policy for material download endpoints using your webserver configuration.
As a workaround, restrict content creation, including material uploads, to trustworthy users only.