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Vulnerability Database/CVE-2026-22181

CVE-2026-22181: OpenClaw DNS Pinning SSRF Vulnerability

CVE-2026-22181 is a DNS pinning bypass vulnerability in OpenClaw that allows SSRF attacks when proxy environment variables are set. This article covers the technical details, affected versions, impact, and mitigation.

Published:

CVE-2026-22181 Overview

OpenClaw versions prior to 2026.3.2 contain a DNS pinning bypass vulnerability (CWE-918: Server-Side Request Forgery) in strict URL fetch paths that allows attackers to circumvent SSRF guards when environment proxy variables are configured. When HTTP_PROXY, HTTPS_PROXY, or ALL_PROXY environment variables are present, attacker-influenced URLs can be routed through proxy behavior instead of pinned-destination routing, enabling access to internal targets reachable from the proxy environment.

Critical Impact

Attackers can bypass DNS pinning protections designed to prevent SSRF attacks, potentially gaining unauthorized access to internal services, cloud metadata endpoints, and other sensitive resources reachable from the proxy environment.

Affected Products

  • OpenClaw versions prior to 2026.3.2
  • Deployments with HTTP_PROXY, HTTPS_PROXY, or ALL_PROXY environment variables configured
  • Web fetch functionality in environments utilizing proxy configurations

Discovery Timeline

  • 2026-03-18 - CVE-2026-22181 published to NVD
  • 2026-03-18 - Last updated in NVD database

Technical Details for CVE-2026-22181

Vulnerability Analysis

This vulnerability represents a Server-Side Request Forgery (SSRF) guard bypass that affects OpenClaw's URL fetch functionality. The issue stems from an incomplete implementation of DNS pinning protections that fails to account for proxy environment variable configurations.

DNS pinning is a security mechanism designed to prevent SSRF attacks by resolving domain names and then ensuring all subsequent connections are made to the initially resolved IP address. This prevents attackers from using DNS rebinding or other techniques to redirect requests to internal resources.

However, when proxy environment variables (HTTP_PROXY, HTTPS_PROXY, or ALL_PROXY) are configured in the deployment environment, the DNS pinning mechanism is effectively bypassed. Instead of connecting directly to the pinned IP address, requests are routed through the configured proxy server, which performs its own DNS resolution and connection handling.

Root Cause

The root cause is an architectural oversight in OpenClaw's URL fetch implementation. The DNS pinning logic was implemented at the application layer but did not account for the lower-level HTTP client behavior when proxy environment variables are present. When a proxy is configured, the HTTP client delegates connection establishment to the proxy server, completely bypassing the application's DNS pinning checks.

This creates a scenario where:

  1. The application resolves a hostname and pins the IP address
  2. The application attempts to connect to the pinned IP
  3. The HTTP client intercepts the request due to proxy configuration
  4. The request is forwarded to the proxy server with the original hostname
  5. The proxy performs its own DNS resolution and connects to any address that hostname resolves to

Attack Vector

An attacker can exploit this vulnerability through network-accessible URL fetch functionality in OpenClaw. The attack requires that the target deployment has proxy environment variables configured.

The exploitation flow involves providing a malicious URL to OpenClaw's web fetch functionality. The attacker controls a DNS server that initially resolves to a benign IP (passing any initial validation), but the proxy server may resolve the domain to a different address, or the attacker can leverage DNS rebinding techniques since the proxy performs independent resolution.

This allows attackers to access internal services such as cloud metadata endpoints (e.g., 169.254.169.254), internal APIs, databases, and other resources that should be protected by SSRF guards. For detailed technical implementation, refer to the GitHub Security Advisory GHSA-8mvx-p2r9-r375.

Detection Methods for CVE-2026-22181

Indicators of Compromise

  • Unusual outbound requests from OpenClaw instances to internal IP ranges (e.g., 10.x.x.x, 172.16.x.x, 192.168.x.x, 169.254.x.x)
  • HTTP requests to cloud metadata endpoints (e.g., 169.254.169.254) originating from OpenClaw processes
  • Proxy logs showing requests to internal hostnames or IP addresses initiated by OpenClaw
  • DNS resolution anomalies where the same domain resolves to different IPs across application and proxy layers

Detection Strategies

  • Monitor proxy server logs for requests to internal IP ranges or sensitive endpoints that originate from OpenClaw services
  • Implement network segmentation monitoring to detect unexpected internal traffic patterns from web-facing OpenClaw deployments
  • Configure alerts for requests to known cloud metadata IP addresses (169.254.169.254, fd00:ec2::254)
  • Review application logs for URL fetch operations targeting suspicious or internal destinations

Monitoring Recommendations

  • Enable detailed logging for all URL fetch operations in OpenClaw to capture full request URLs and destinations
  • Configure proxy servers to log source application identifiers alongside request details
  • Implement egress filtering with logging to detect attempts to reach internal networks from OpenClaw instances
  • Set up anomaly detection for unusual patterns in outbound request frequency or destination diversity

How to Mitigate CVE-2026-22181

Immediate Actions Required

  • Upgrade OpenClaw to version 2026.3.2 or later, which contains the fix for this vulnerability
  • Audit current deployments to identify instances where proxy environment variables are configured
  • Review and restrict access to internal services from systems running vulnerable OpenClaw versions
  • Implement network-level SSRF protections as a defense-in-depth measure

Patch Information

The vulnerability has been addressed in OpenClaw version 2026.3.2. The fix ensures that DNS pinning protections are enforced regardless of proxy configuration by implementing pinning at a layer that cannot be bypassed by HTTP client proxy behavior. For technical details on the patch implementation, see the GitHub Commit Update.

Additional information is available in the VulnCheck Advisory on DNS Pinning Bypass.

Workarounds

  • Remove or unset HTTP_PROXY, HTTPS_PROXY, and ALL_PROXY environment variables from OpenClaw deployment environments if proxy usage is not required
  • Implement network-level egress filtering to block requests to internal IP ranges from OpenClaw instances
  • Deploy a dedicated proxy server with strict allowlists that prevent access to internal resources
  • Use network segmentation to isolate OpenClaw instances from sensitive internal services
bash
# Configuration example
# Unset proxy environment variables for OpenClaw service
unset HTTP_PROXY
unset HTTPS_PROXY
unset ALL_PROXY
unset http_proxy
unset https_proxy
unset all_proxy

# Alternative: Configure OpenClaw service without proxy inheritance
# In systemd service file, add:
# Environment="HTTP_PROXY="
# Environment="HTTPS_PROXY="
# Environment="ALL_PROXY="

Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.

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