CVE-2026-53840

Name of the Vulnerable Software and Affected Versions OpenClaw versions prior to 2026.5.12

Description An information disclosure issue exists in streamable-http MCP servers that forwards operator-configured custom headers during cross-origin redirects. Attackers controlling or compromising an MCP endpoint can redirect requests to exfiltrate sensitive headers, such as API keys or tenant-routing credentials, to attacker-controlled origins. This occurs in deployments where an MCP server is configured with transportType: "streamable-http" and sensitive custom headers under mcp.servers.*.headers. The issue is limited to configured MCP Streamable HTTP servers using custom headers and does not expose unrelated credentials.

Recommendations Update to version 2026.5.12. As a temporary mitigation, avoid using custom MCP headers with servers that are not fully trusted. Rotate any MCP-specific credentials that may have been exposed by a redirecting endpoint.