BragJack Flaw Let an Extension Hijack Browser AI Assistants
Security researchers at Forever Security discovered a new attack method called BragJack that let an ordinary browser extension take control of the AI assistants built into five popular browsers.
According to the reports, the affected products were Google Chrome with Gemini, Microsoft Edge, Opera Neon, Perplexity Comet, and the Claude extension in Chrome. Researcher Gal Weizman said any user running one of these browsers with at least one extension installed was potentially at risk.
Unlike earlier types of attacks, the researchers did not need to hide instructions inside content the AI would read. Instead, they exploited a design flaw: extensions could cross the boundary meant to separate them from the highly privileged AI agent and send it commands directly until it complied.
In one example involving Chrome and Gemini, the researchers said they were able to take screenshots, access local files, and activate the camera or microphone without the user clicking anything.
The companies involved—Google, Microsoft, Opera, Anthropic, and Perplexity—each confirmed the vulnerabilities and paid bug bounties ranging from 600 to 7,000 US dollars. Google and Microsoft also issued official security identifiers for the flaws.
According to the sources, all reported issues have since been fixed. It is not known how many people were actually affected before the flaws were closed.
WHY IT MATTERS
The case shows that AI assistants built into browsers can have far-reaching access to personal data, and that even a seemingly harmless extension could be enough to abuse that access.
WHAT YOU CAN DO NOW
- Only install a few trusted extensions Check reviews and the publisher before installing any extension. Fewer extensions mean a smaller target for attacks like this one.
- Keep your browser updated Turn on automatic updates in your browser settings. Flaws like this one are usually fixed through an update once they become known.
- Remove extensions you no longer use Check your browser's extension list regularly and delete anything you don't need anymore. Every extra extension is a possible entry point.
- Be careful with built-in AI features Think about what data the browser's AI assistant can see or change before using it. Turn the feature off if you don't use it regularly.