UNIVERSAL CODE EXECUTION BY CHAINING MESSAGES IN BROWSER EXTENSIONS

Summary from the TLDR Web Dev newsletter

By chaining various messaging APIs in browsers and browser extensions, it's possible to achieve 'universal code execution', breaking Same Origin Policy and browser sandbox. This vulnerability allows malicious web pages to communicate with an extension's content script and then relay messages to the background script, which can further communicate with a native application on the host operating system. This means that the chain can execute arbitrary code on the victim's machine.