Bruno is an open source IDE for exploring and testing APIs. A bug in the assertion runtime caused assert expressions to run in Developer Mode, even if Safe Mode was selected. The bug resulted in the sandbox settings to be ignored for the particular case where a single request is run/sent. This vulnerabilitys 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 collection. The vulnerability is fixed in 1.39.1.
The product uses a web-client protection mechanism such as a Content Security Policy (CSP) or cross-domain policy file, but the policy includes untrusted domains with which the web client is allowed to communicate.
If a cross-domain policy file includes domains that should not be trusted, such as when using wildcards under a high-level domain, then the application could be attacked by these untrusted domains. In many cases, the attack can be launched without the victim even being aware of it.