CVE-2025-6514: 
JavaScript vulnerability analysis and mitigation

CVE-2025-6514 is a critical security vulnerability (CVSS 9.6) discovered in mcp-remote, a popular tool used by Model Context Protocol (MCP) clients. The vulnerability affects mcp-remote versions 0.0.5 to 0.1.15 and was discovered and disclosed by the JFrog Security Research team. The issue allows attackers to trigger arbitrary OS command execution on machines running mcp-remote when connecting to untrusted MCP servers, potentially leading to full system compromise (JFrog Blog).

The vulnerability stems from improper handling of the authorization_endpoint URL received during OAuth flow initialization. When mcp-remote connects to a malicious MCP server, the server can respond with a specially crafted authorization_endpoint URL value that, when processed by the open() function, leads to command injection. On Windows systems, this allows for arbitrary OS command execution with full parameter control through PowerShell's subexpression evaluation feature. On macOS and Linux, the vulnerability enables execution of arbitrary executables with limited parameter control (JFrog Blog, JFrog Research).

The vulnerability affects any user connecting to untrusted or insecure MCP servers using affected versions of mcp-remote. The impact is particularly severe as it enables full system compromise through arbitrary command execution. The tool is widely used in the AI community, especially with applications like Claude Desktop, Cursor, and Windsurf that rely on MCP for external data source connections (JFrog Blog).

Two primary mitigation strategies are recommended: 1) Update mcp-remote to version 0.1.16, which includes a fix for this vulnerability (this is the recommended solution), 2) Only connect to trusted MCP Servers using HTTPS (secure connection). The vulnerability has been patched by Glen Maddern, mcp-remote's primary maintainer (JFrog Blog, GitHub Commit).

The discovery has prompted several LLM hosts to enhance their security measures. Cursor and Windsurf have added direct remote MCP Server connection capabilities, while Anthropic has extended this feature to Claude Desktop users with paid subscriptions. The vulnerability has raised awareness about the importance of secure connections to MCP servers in the growing MCP ecosystem (JFrog Blog).