SSRF in Cern Indico

CVE-2026-25738

Indico is an event management system that uses Flask-Multipass, a multi-backend authentication system for Flask. Versions prior to 3.3.10 are vulnerable to server-side request forgery. Indico makes outgoing requests to user-provides URLs in various places. This is mostly intentional and part of Indico's functionality but is never intended to let users access "special" targets such as localhost or cloud metadata endpoints. Users should upgrade to version 3.3.10 to receive a patch. Those who do not have IPs that expose sensitive data without authentication (typically because they do not host Indico on AWS) are not affected. Only event organizers can access endpoints where SSRF could be used to actually see the data returned by such a request. For those who trust their event organizers, the risk is also very limited. For additional security, both before and after patching, one may also use the common proxy-related environment variables (in particular `http_proxy` and `https_proxy`) to force outgoing requests to go through a proxy that limits requests in whatever way you deem useful/necessary. These environment variables would need to be set both on the indico-uwsgi and indico-celery services.

Vulnerability class: TOCTOU (Time-of-Check to Time-of-Use)

Published 2026-02-19 · last modified 2026-06-17.