CVE-2025-59376: 
Python vulnerability analysis and mitigation

CVE-2025-59376 is a critical security vulnerability discovered in the feiskyer/mcp-kubernetes-server package. The vulnerability allows an attacker to bypass command validation by chaining commands using shell metacharacters, enabling arbitrary OS command execution on the host running the MCP server. The vulnerability was identified in version v0.1.11 and earlier of the package (GitHub CVE).

The vulnerability stems from insufficient input validation in the kubectl tool implementation. The validation logic only inspects the first element of the command (cmd[0]) to ensure it is kubectl, but fails to sanitize the rest of the input for shell metacharacters. This allows attackers to chain malicious commands after a legitimate kubectl command using semicolons (;), leading to command injection (GitHub CVE).

Successful exploitation allows an unauthenticated attacker with access to the MCP endpoint to achieve full Remote Code Execution on the server host under the privileges of the MCP server process. This can lead to complete system compromise, data theft, financial loss, and can be used as a pivot point to attack the entire Kubernetes cluster and internal network (GitHub CVE).

The recommended mitigations include: 1) Rewriting the underlying command.py module to avoid using shell=True with subprocess.run and instead passing commands as a list, 2) Implementing strict validation of all user-provided arguments against an allow-list of known-safe kubectl subcommands and parameters, and 3) Stripping or rejecting command chaining metacharacters (&, |, ;, $, `) (GitHub CVE).