Executive brief
OpenClaw's sandbox browser component launched a VNC server without authentication for remote observation sessions. Attackers with access to the host's loopback interface could connect to the exposed noVNC port and view or interact with browser activity without requiring credentials, potentially exposing sensitive activity within the sandboxed environment.
Technical details
The vulnerability is a missing authentication control (CWE-306) in OpenClaw's sandbox browser entrypoint script. The x11vnc server was launched with the -nopw flag, disabling VNC password authentication for noVNC observer sessions. By default, the noVNC port is bound to localhost (127.0.0.1) only; however, attackers with local access to the host can connect to the exposed port without credentials and observe or interact with the sandboxed browser. The fix requires enabling x11vnc's -rfbauth parameter, generating per-container noVNC passwords, and injecting credentials via environment variables. Patches are available in versions 2026.2.21 and later.
Affected products
- OpenClaw OpenClaw <2026.2.21
Timeline
- 2026-02-21: disclosed
- 2026-02-21: patched: Version 2026.2.21 and later
- 2026-03-21: advisory