Executive Summary

CVE-2026-41403 is an access control bypass vulnerability in OpenClaw versions before 2026.3.31. The issue occurs in the diffs viewer component when the setting allowRemoteViewer is disabled. OpenClaw incorrectly classifies proxied remote requests as local loopback connections, which allows attackers to bypass access controls and gain unauthorized access to the remote viewer functionality.

This misclassification happens because the system trusts certain proxy headers or fails to properly resolve the client's real IP address, leading to incorrect security decisions.

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Impact Analysis

This vulnerability can allow unauthorized users to access the diffs viewer remotely even when remote access is supposed to be disabled. Attackers can exploit the misclassification of proxied requests to bypass intended access restrictions.

As a result, sensitive information that should be restricted to local or authorized users could be exposed to unauthorized remote parties, potentially leading to information disclosure or further exploitation.

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Detection Guidance

This vulnerability involves misclassification of proxied remote requests as local loopback connections in the OpenClaw diffs viewer when the allowRemoteViewer setting is disabled. Detection involves monitoring network traffic for proxied requests that are incorrectly treated as local requests.

To detect exploitation attempts, you can look for unusual access patterns to the diffs viewer component, especially requests coming from remote IP addresses that are being treated as loopback (127.0.0.1 or ::1).

Suggested commands include inspecting network connections and logs for such anomalies. For example:

• Use netstat or ss to list active connections and check for unexpected remote connections to the OpenClaw service ports.
• Use tcpdump or Wireshark to capture and analyze traffic to the OpenClaw diffs viewer endpoint, filtering for requests with suspicious X-Forwarded-For headers or proxied IP addresses.
• Check application logs for access attempts where the client IP is logged as loopback but the source IP is remote or proxied.
• Example command to monitor connections on port 80 or 443 (adjust port as needed): sudo netstat -tnp | grep ':80\|:443'
• Example tcpdump command to capture HTTP traffic to the diffs viewer endpoint: sudo tcpdump -i any tcp port 80 and dst host <OpenClaw_IP> -w capture.pcap

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Compliance Impact

The provided information does not specify any direct impact of CVE-2026-41403 on compliance with common standards and regulations such as GDPR or HIPAA.

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Mitigation Strategies

The primary mitigation is to upgrade OpenClaw to version 2026.3.31 or later, where the vulnerability has been fixed by improving client IP resolution and access control logic.

If upgrading immediately is not possible, consider the following temporary mitigations:

• Ensure the allowRemoteViewer setting is explicitly disabled to prevent remote viewer access.
• Configure trusted proxies correctly to avoid trusting unverified proxy headers.
• Restrict network access to the OpenClaw diffs viewer component to trusted internal IP addresses only, using firewall rules or network segmentation.
• Monitor logs and network traffic for suspicious proxied requests that may be attempting to bypass access controls.

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