CVE-2024-29891: ZITADEL's Improper Content-Type Validation Leads to Account Takeover via Stored XSS + CSP Bypass

ZITADEL users can upload their own avatar image and various image types are allowed.

Due to a missing check, an attacker could upload HTML and pretend it is an image to gain access to the victim’s account in certain scenarios. A possible victim would need to directly open the supposed image in the browser, where a session in ZITADEL needs to be active for this exploit to work.

The exploit could only be reproduced if the victim was using Firefox. Chrome, Safari as well as Edge did not execute the code.