Flask-AppBuilder is an application development framework, built on top of Flask. A Cross-Site Scripting (XSS) vulnerability has been discovered on the OAuth login page. An attacker could trick a user to follow a specially crafted URL to the OAuth login page. This URL could inject and execute malicious javascript code that would get executed on the user's browser. This issue was introduced on 4.1.4 and patched on 4.2.1.