PraisonAI Browser Bridge Critical Session Hijacking

The National Vulnerability Database (NVD) has issued a critical advisory for PraisonAI and praisonaiagents, multi-agent systems that leverage browser automation. Designated CVE-2026-40289, this vulnerability allows for unauthenticated remote session hijacking within the browser bridge, specifically affecting versions below 4.5.139 of PraisonAI and 1.5.140 of praisonaiagents. The core issue lies in a missing authentication mechanism and a bypassable origin check on the /ws WebSocket endpoint.

According to the NVD, the server, which binds to 0.0.0.0 by default, only validates the Origin header when it’s present. This oversight means any non-browser client can connect without restriction by simply omitting the header. An unauthenticated network attacker can then send a start_session message, effectively hijacking the first idle browser-extension WebSocket. This grants them unauthorized remote control over connected browser automation sessions, enabling data exfiltration of sensitive page context and automation results, and potential misuse of model-backed browser actions from any network-reachable bridge. This is a severe oversight, categorized under CWE-306 (Missing Authentication for Critical Function), and has been patched in the specified updated versions.