2FAuth is a web app to manage Two-Factor Authentication (2FA) accounts and generate their security codes. Versions prior to 5.4.1 are vulnerable to stored cross-site scripting due to improper headers in direct access to uploaded SVGs. The application allows uploading images in several places. One of the accepted types of image is SVG, which allows JS scripting. Therefore, by uploading a malicious SVG which contains JS code, an attacker which is able to drive a victim to the uploaded image could compromise that victim's session and access to their tokens. Version 5.4.1 contains a patch for the issue.
The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.