CVE-2026-41403: OpenClaw Auth Bypass Vulnerability

CVE-2026-41403 Overview

CVE-2026-41403 is an authorization bypass vulnerability in OpenClaw before version 2026.3.31. The application misclassifies proxied remote requests as loopback connections in the diffs viewer when the allowRemoteViewer setting is disabled. This flaw allows attackers to bypass access controls by sending proxied requests that are incorrectly identified as local loopback traffic, circumventing intended remote viewer restrictions.

Critical Impact
Unauthorized access to the diffs viewer functionality through access control bypass, potentially exposing sensitive code changes and repository information to remote attackers.

Affected Products

OpenClaw versions prior to 2026.3.31
OpenClaw diffs viewer component with allowRemoteViewer disabled
Deployments behind proxy servers or reverse proxies

Discovery Timeline

2026-04-28 - CVE CVE-2026-41403 published to NVD
2026-04-28 - Last updated in NVD database

Technical Details for CVE-2026-41403

Vulnerability Analysis

This vulnerability is classified under CWE-807 (Reliance on Untrusted Inputs in a Security Decision). The OpenClaw diffs viewer component relies on request metadata to determine whether an incoming connection originates from the local loopback interface or a remote source. When requests pass through a proxy server, the application incorrectly trusts proxy-provided headers or connection metadata, leading to misclassification of the request origin.

When allowRemoteViewer is set to false, the application is intended to restrict access to the diffs viewer to local connections only. However, due to improper validation of connection origin, proxied requests from remote sources are erroneously classified as local loopback traffic. This allows remote attackers to access functionality that should be restricted to local users.

Root Cause

The root cause of this vulnerability lies in the application's reliance on untrusted inputs to make security decisions. The diffs viewer component does not properly distinguish between actual loopback connections and proxied requests that merely appear to originate from localhost. The application likely trusts HTTP headers such as X-Forwarded-For, X-Real-IP, or similar proxy headers without adequate validation, or incorrectly interprets the connection source address when operating behind a reverse proxy.

Attack Vector

The attack is network-based and requires the target OpenClaw instance to be accessible through a proxy server. An attacker can craft HTTP requests that are routed through a proxy, causing the application to misidentify the remote connection as a local loopback request. This bypasses the allowRemoteViewer restriction, granting unauthorized access to the diffs viewer functionality.

The attack involves sending requests through a proxy server to the OpenClaw instance, where the application misinterprets the proxied connection as originating from localhost (127.0.0.1 or ::1). Technical details regarding the specific exploitation mechanism can be found in the GitHub Security Advisory.

Detection Methods for CVE-2026-41403

Indicators of Compromise

Unexpected access to the diffs viewer from external IP addresses when allowRemoteViewer is disabled
Log entries showing diffs viewer access classified as "local" but originating from proxy connections
Anomalous request patterns to /diffs or similar viewer endpoints with proxy headers present

Detection Strategies

Monitor access logs for diffs viewer requests and correlate with actual source IP addresses
Implement alerting for any remote access attempts to restricted viewer functionality
Deploy web application firewall (WAF) rules to detect proxy header manipulation attempts
Review authentication and access control logs for discrepancies between classified origin and actual source

Monitoring Recommendations

Enable verbose logging for the diffs viewer component to capture request origin details
Configure SIEM rules to alert on diffs viewer access from non-local IP ranges
Implement network-level monitoring for traffic patterns indicative of proxy-based access control bypass attempts

How to Mitigate CVE-2026-41403

Immediate Actions Required

Upgrade OpenClaw to version 2026.3.31 or later immediately
Audit access logs for evidence of unauthorized diffs viewer access
Review and restrict network access to OpenClaw instances at the firewall level
Consider temporarily disabling the diffs viewer functionality until patching is complete

Patch Information

The vulnerability is addressed in OpenClaw version 2026.3.31. The fix ensures proper validation of connection origin and prevents proxy headers from being used to bypass access controls. The security patch is available via the GitHub commit 30a1690323088fd291abd11643a264a6828a002c.

Additional information is available in the GitHub Security Advisory and the VulnCheck Advisory.

Workarounds

Implement network-level access controls to restrict access to the OpenClaw instance to trusted IP ranges only
Configure reverse proxy to strip or sanitize untrusted origin headers before forwarding to OpenClaw
Temporarily enable authentication requirements for diffs viewer access regardless of source
Deploy a WAF rule to block requests with suspicious proxy header combinations

bash

# Example: Restrict access to OpenClaw at the firewall level (iptables)
# Allow only trusted internal network access to OpenClaw port
iptables -A INPUT -p tcp --dport 8080 -s 10.0.0.0/8 -j ACCEPT
iptables -A INPUT -p tcp --dport 8080 -j DROP