OpenClaw Loopback Protection Bypass Vulnerability via Trailing-Dot Localhost in CDP Discovery

A loopback protection bypass vulnerability has been identified in OpenClaw versions prior to 2026.4.2. The issue arises because the application fails to properly normalize trailing-dot localhost hosts in remote Chrome DevTools Protocol (CDP) discovery responses. This oversight allows attackers to craft malicious discovery responses that include localhost. to redirect authenticated browser control to localhost endpoints, potentially exposing sensitive browser state.

Impact

Exploitation of this vulnerability could lead to unauthorized access to localhost-resolving endpoints, allowing exposure of browser state backed by localhost.

Reproduction

The vulnerability can be reproduced by sending a remote CDP discovery response that includes a trailing-dot localhost host, such as 'localhost.'. This response will bypass OpenClaw's loopback normalization, allowing a non-loopback remote CDP profile to redirect connections back to localhost.

Remediation

Users can update to OpenClaw version 2026.4.2 or later, where this vulnerability has been patched.