Argocd-mcp 0.8.0 Unauthenticated Remote Code Execution

Executive Summary

CVE-2026-82456 is a critical authentication bypass in argocd-mcp 0.8.0 where the HTTP server binds to all network interfaces and accepts unauthenticated MCP sessions when ARGOCD_API_TOKEN is set. Attackers on the same network can exploit this to use the operator's stored token to create applications, request syncs, and modify Argo CD resources without credentials.

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Detection Guidance

Check if argocd-mcp 0.8.0 is running and listening on all network interfaces (0.0.0.0) by using commands like 'netstat -tulnp | grep argocd-mcp' or 'ss -tulnp | grep argocd-mcp'. Verify if the service accepts unauthenticated connections by attempting to access it from a different host on the network.

Inspect the version of argocd-mcp installed using 'mcp-for-argocd --version' or by checking package managers like 'pip show argocd-mcp'. If version 0.8.0 or below is detected, the system is likely vulnerable.

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Impact Analysis

An attacker could deploy unauthorized Kubernetes manifests, modify or delete applications, or exfiltrate sensitive data using the compromised Argo CD token. This could lead to full system compromise, data breaches, or service disruption if the attacker gains control over deployed resources.

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Compliance Impact

This vulnerability could lead to unauthorized access and data breaches, violating GDPR's data protection requirements and HIPAA's security rules. Organizations may face fines, legal penalties, and reputational damage due to non-compliance resulting from unauthorized resource modifications or data exposure.

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Mitigation Strategies

Upgrade argocd-mcp to version 0.9.0 or later immediately, as this version restricts the listener to localhost and adds authentication requirements.

If upgrading is not immediately possible, restrict the HTTP transport binding to localhost by modifying the service configuration or using firewall rules to block external access to the vulnerable port.

Disable or remove the ARGOCD_API_TOKEN environment variable if it is not required for operation, as this reduces the attack surface.

Monitor network traffic for unauthorized access attempts or unusual MCP session creation, especially from external hosts.

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