Bruno is an open source IDE for exploring and testing APIs. Prior to 1.39.1, the custom tool-tip components which internally use react-tooltip were setting the content (in this case the Environment name) as raw HTML which then gets injected into DOM on hover. This, combined with loose Content Security Policy restrictions, allowed any valid HTML text containing inline script to get executed on hovering over the respective Environment's name. This vulnerability's attack surface is limited strictly to scenarios where users import collections from untrusted or malicious sources. The exploit requires deliberate action from the user—specifically, downloading and opening an externally provided malicious Bruno or Postman collection export and the user hovers on the environment name. This vulnerability is fixed in 1.39.1.
The product receives input from an upstream component, but it does not neutralize or incorrectly neutralizes special characters such as "<", ">", and "&" that could be interpreted as web-scripting elements when they are sent to a downstream component that processes web pages.