PraisonAI has a Browser Server WebSocket origin validation bypass via unanchored regex (patch bypass of CVE-2026-40289 / GHSA-8x8f-54wf-vv92)

Summary

praisonai/browser/server.py validates incoming WebSocket connections using a Chrome

extension Origin check. The regex chrome-extension://[a-z0-9]{32} is applied with

re.match(), which only anchors at the start of the string, not the end. Any Origin

header with more than 32 alphanumeric characters after chrome-extension:// — including

non-alphanumeric trailing characters — passes the check.

This is a patch bypass of GHSA-8x8f-54wf-vv92. That advisory triggered the addition

of origin validation; this finding shows the validation is bypassable by any WebSocket

client that forges an Origin header. After bypassing, the attacker can send start_session

commands that are executed by any Chrome extension currently connected to the server —

causing the extension to perform arbitrary browser automation including cookie theft and

screenshot capture.

Details

Vulnerable code — browser/server.py line 186:

elif parsed_origin.scheme == "chrome-extension" and \
     re.match(r"chrome-extension://[a-z0-9]{32}", origin):
    is_allowed = True