CVE-2026-55536: PraisonAI has a Browser Server WebSocket origin validation bypass via unanchored regex (patch bypass of CVE-2026-40289 / GHSA-8x8f-54wf-vv92)

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.