CVE-2025-59377: 
Python vulnerability analysis and mitigation

CVE-2025-59377 is a critical security vulnerability discovered in the feiskyer/mcp-kubernetes-server package. The vulnerability affects version v0.1.11 and earlier of the package, which is designed to provide limited access to a Kubernetes cluster through an MCP tool named kubectl. The issue was discovered and disclosed in early 2025 (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 to ensure it is kubectl but fails to sanitize the rest of the input for shell metacharacters. This allows attackers to bypass command validation by chaining commands using shell metacharacters (e.g., semicolons), enabling arbitrary OS command execution on the host running the MCP server (GitHub CVE).

The vulnerability allows an unauthenticated attacker with access to the MCP endpoint to achieve full Remote Code Execution (RCE) 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 mitigation involves two key fixes: 1) Rewriting the command.py module to avoid using shell=True with subprocess.run and instead passing commands and arguments as a list, and 2) Implementing strict validation of all user-provided arguments against an allow-list of known-safe kubectl subcommands and parameters, with command chaining metacharacters being stripped or rejected (GitHub CVE).