CVE-2026-82456 in argocd-mcp
Summary
by MITRE • 08/29/2026
argocd-mcp 0.8.0 binds its HTTP transport to every network interface and accepts MCP sessions without requiring caller credentials when ARGOCD_API_TOKEN is configured. Attackers who can reach the listener can invoke the full tool surface using the operator's stored token to create applications, request syncs, and modify Argo CD resources.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 08/29/2026
The vulnerability in argocd-mcp version 0.8.0 represents a critical misconfiguration that exposes sensitive Kubernetes cluster management capabilities to unauthorized access through insecure network binding and authentication bypass mechanisms. The core technical flaw lies in the application's default behavior of binding its HTTP transport interface to all available network interfaces, commonly referred to as zero-address or 0.0.0.0 binding. This configuration choice effectively makes the service accessible from any external network segment that can route traffic to the host machine, rather than restricting access solely to localhost or specific trusted internal subnets. When combined with the presence of an ARGOCD_API_TOKEN environment variable, which is used for authenticating against the Argo CD API server, the application creates a direct bridge between unauthenticated external requests and privileged cluster operations. The system accepts Model Context Protocol sessions without requiring additional caller credentials beyond the existence of this token in the environment, effectively treating any incoming connection as authorized if it can reach the listener endpoint.
From an operational impact perspective, this vulnerability allows attackers who have network connectivity to the affected host to invoke the full tool surface exposed by argocd-mcp. Since the operator's stored API token is utilized for backend authentication with Argo CD, successful exploitation grants the attacker the same level of privileges as the service account associated with that token. This typically includes high-privilege capabilities such as creating new applications within the GitOps workflow, requesting synchronization operations to deploy potentially malicious codebases into production environments, and modifying existing Argo CD resources like application sets or project configurations. The ability to create applications enables attackers to inject arbitrary Helm charts or Kustomize overlays that can compromise containerized workloads running in the cluster. Requesting syncs allows for immediate deployment of these artifacts without manual approval workflows if automated syncing is enabled, accelerating the attack chain significantly.
This vulnerability maps directly to CWE-284 Improper Access Control and CWE-798 Use of Hard-coded Credentials within the context of environment variable reliance. The binding to all interfaces aligns with CWE-605 Multiple Bindings which increases the attack surface unnecessarily. In terms of offensive security frameworks, this scenario is consistent with MITRE ATT&CK technique T1133 External Remote Services where an attacker leverages exposed services for lateral movement or initial access. Furthermore, the ability to create applications and sync them relates to T1505 Server Software Component which involves installing web shells or backdoors via legitimate software components like Argo CD application definitions. The exploitation path does not require complex payload crafting but rather relies on network reachability and correct formatting of MCP session requests that trigger the underlying tool execution functions.
Mitigation strategies must address both the network exposure and the authentication model immediately. Administrators should configure argocd-mcp to bind exclusively to localhost or a specific internal management interface using explicit host configuration parameters if available, ensuring external networks cannot directly reach the service port. If remote access is required for legitimate operations, it should be proxied through an authenticated reverse proxy such as Nginx with mutual TLS or OAuth2 integration that validates caller identity before forwarding requests to argocd-mcp. The ARGOCD_API_TOKEN environment variable represents a high-value secret and must be treated with the same security controls as any other credential; this includes using Kubernetes secrets mounted as files rather than plain text environment variables where possible, rotating tokens regularly, and applying least-privilege principles by restricting the token's permissions to only those necessary for specific tasks. Additionally, implementing network policies in the container orchestration layer can restrict ingress traffic to known management CIDRs, providing a defense-in-depth measure against unauthorized access attempts even if the application binding remains permissive during transition periods.