Executive brief
OpenClaw is a browser automation and control tool. Before version 2026.4.2, the software failed to properly validate localhost addresses in remote discovery responses, allowing an attacker to craft a malicious response that redirects authenticated browser connections back to the local machine, potentially exposing sensitive browser state and session data.
Technical details
OpenClaw's remote Chrome DevTools Protocol (CDP) discovery implementation fails to normalize trailing-dot localhost hosts (e.g., "localhost.") before applying loopback protection checks, allowing a network-reachable attacker to bypass these protections via a hostile CDP discovery response. The vulnerability stems from incomplete hostname normalization in the discovery response parsing logic. An attacker can craft a malicious CDP discovery response returning a trailing-dot localhost address, which bypasses the loopback checks and causes the client to establish an authenticated connection to a localhost endpoint. This exposes browser automation state and authenticated sessions to local attackers. The vulnerability was patched in version 2026.4.2 (commit 9c22d636697336a6b22b0ae24798d8b8325d7828).
Affected products
- OpenClaw OpenClaw <= 2026.4.1
Timeline
- 2026-04-02: disclosed
- 2026-04-28: patched: version 2026.4.2 released
- 2026-04-28: advisory