CVE-2025-53355: MCP Server Kubernetes RCE Vulnerability

CVE-2025-53355 Overview

A critical command injection vulnerability has been identified in MCP Server Kubernetes, an MCP Server designed to connect to and manage Kubernetes clusters. The vulnerability stems from unsanitized input parameters being passed directly to child_process.execSync calls, enabling attackers to inject arbitrary system commands. Successful exploitation can lead to remote code execution under the server process's privileges, potentially compromising the entire Kubernetes cluster management infrastructure.

Critical Impact

Attackers can achieve remote code execution by injecting malicious commands through unsanitized input parameters, potentially gaining full control over the server process and managed Kubernetes clusters.

Affected Products

• MCP Server Kubernetes versions prior to 2.5.0
• Related MCP Servers using similar execSync patterns (including git-mcp-server)

Discovery Timeline

• 2025-07-08 - CVE-2025-53355 published to NVD
• 2026-04-15 - Last updated in NVD database

Technical Details for CVE-2025-53355

Vulnerability Analysis

This command injection vulnerability (CWE-77) exists due to the unsafe use of Node.js child_process.execSync and exec functions with user-controlled input. The MCP Server Kubernetes application fails to properly sanitize input parameters before constructing shell commands, allowing attackers to break out of the intended command context and execute arbitrary system commands.

The vulnerability is particularly dangerous in Kubernetes management contexts, as the server process typically runs with elevated privileges necessary for cluster operations. An attacker who successfully exploits this vulnerability could execute commands with the same privileges as the MCP server, potentially leading to cluster-wide compromise, data exfiltration, or lateral movement within the infrastructure.

Root Cause

The root cause is the direct concatenation of user-supplied input into shell command strings passed to child_process.execSync. This synchronous execution method interprets the entire string as a shell command, allowing shell metacharacters and command separators (such as ;, |, &&, or backticks) to be processed. Without proper input sanitization or parameterization, malicious input can escape the intended command structure and execute arbitrary commands.

Attack Vector

The attack vector is network-based, requiring user interaction. An attacker can craft malicious input containing shell metacharacters that, when processed by the vulnerable execSync calls, execute arbitrary commands on the underlying system. The attack targets helm operations and kubectl apply functionality within the MCP server, where user-controlled parameters are passed to shell commands without proper escaping.

For example, an attacker could supply a malicious chart name, namespace, or resource parameter containing shell command injection payloads that would be executed when the server processes the request.

The security fix migrates from execSync to execFileSync with arguments passed as an array, which prevents shell interpretation of special characters:

-import { execSync } from "child_process";
+import { execFileSync } from "child_process";
 import { writeFileSync, unlinkSync } from "fs";
 import yaml from "yaml";
-import { HelmInstallOperation, HelmOperation, HelmResponse, HelmUpgradeOperation } from "../models/helm-models.js";
+import {
+  HelmInstallOperation,
+  HelmOperation,
+  HelmResponse,
+  HelmUpgradeOperation,
+} from "../models/helm-models.js";
 
 export const installHelmChartSchema = {
   name: "install_helm_chart",

Source: GitHub Commit - helm-operations.ts fix

Similar fixes were applied across multiple files:

 import { KubernetesManager } from "../types.js";
-import { execSync } from "child_process";
+import { execFileSync } from "child_process";
 import { McpError, ErrorCode } from "@modelcontextprotocol/sdk/types.js";
 import * as fs from "fs";
 import * as path from "path";

Source: GitHub Commit - kubectl-apply.ts fix

Detection Methods for CVE-2025-53355

Indicators of Compromise

• Unusual command execution patterns originating from the MCP server process
• Presence of shell metacharacters (;, |, &&, `, $()) in helm chart names, namespace parameters, or kubectl resource specifications
• Unexpected child processes spawned by the Node.js MCP server application
• Anomalous network connections or data exfiltration attempts from the server

Detection Strategies

• Monitor process execution trees for unexpected child processes spawned by the MCP server
• Implement application-level logging to capture all input parameters passed to helm and kubectl operations
• Deploy file integrity monitoring on the MCP server installation directory to detect unauthorized modifications
• Use endpoint detection and response (EDR) solutions to identify command injection attack patterns

Monitoring Recommendations

• Enable audit logging for all Kubernetes API calls made through the MCP server
• Configure alerts for processes executed with shell metacharacters in command arguments
• Monitor for privilege escalation attempts or lateral movement following MCP server process compromise
• Implement network segmentation monitoring between the MCP server and Kubernetes cluster endpoints

How to Mitigate CVE-2025-53355

Immediate Actions Required

• Upgrade MCP Server Kubernetes to version 2.5.0 or later immediately
• Audit existing MCP server logs for signs of exploitation attempts
• Review and restrict network access to MCP server endpoints
• Implement input validation at the network perimeter to filter requests containing shell metacharacters

Patch Information

The vulnerability is fixed in MCP Server Kubernetes version 2.5.0. The patch replaces unsafe execSync calls with execFileSync, passing command arguments as an array rather than a concatenated string. This approach prevents shell interpretation of user-supplied input.

For detailed patch information, refer to the GitHub Security Advisory and the security patch commit.

Workarounds

• If immediate patching is not possible, restrict access to the MCP server to trusted internal networks only
• Implement a web application firewall (WAF) or API gateway with rules to block requests containing shell metacharacters
• Run the MCP server with minimal required privileges using principle of least privilege
• Consider temporarily disabling helm and kubectl apply functionality until the patch can be applied

# Configuration example - Restrict MCP server network access
# Add firewall rules to limit access to trusted IPs only
iptables -A INPUT -p tcp --dport 3000 -s 10.0.0.0/8 -j ACCEPT
iptables -A INPUT -p tcp --dport 3000 -j DROP

# Alternatively, use network policies in Kubernetes
# to restrict ingress to the MCP server pod