Mercury: Unauthenticated Remote Code Execution via /api/kernels

Mercury runs a JupyterLab server with anonymous access by default mercuryapp/main.py sets --IdentityProvider.token='' when no --token/MERCURYTOKEN is given; when tokenless it also sets --ServerApp.disablecheckxsrf=True. It relies on a blocklist mercuryapp/blockhandler.py BLOCKEDPATTERNS: /lab,...