Monkeytype is a minimalistic and customizable typing test. In 25.49.0 and earlier, there is improper handling of user input which allows an attacker to execute malicious javascript on anyone viewing a malicious quote submission. quote.text and quote.source are user input, and they're inserted straight into the DOM. If they contain HTML tags, they will be rendered (after some escaping using quotes and textarea tags).
Monkeytype is a minimalistic and customizable typing test. In versions 25.36.0 and prior, improper handling of user input when loading a saved custom text results in XSS. This issue has been fixed in version 25.44.0.