GCVE-110-VULN-PYPI-2026-000643

If you run aimarket-platon without PLATON_STEER_TOKEN, outside production mode, behind a reverse proxy, tunnel or port forward on the same host, and that proxy runs as the same user as the server or the host is not Linux, every caller of the proxy can steer and project the shared world (POST /api/steer, /api/project, the beacon checkpoint, the platon.steer@v1 and platon.project@v1 capabilities and the websocket writes). Without a token the server accepts writes only from callers it judges local (main._write_authorized, main._local_caller). The test added in 0.1.5 (main._caller_is_this_user) tells a proxy from a local client only by the owner of its socket in /proc/net/tcp: a proxy running as the server's user passes it, and where /proc/net/tcp does not exist (macOS, Windows) every caller passes it. Earlier versions accepted every writer (GCVE-110-VULN-PYPI-2026-000630). Affects 0.1.0 through 0.1.5.