A critical security vulnerability (CVE-2025-6514) has been identified in the widely used open-source package mcp-remote, exposing hundreds of thousands of systems to the risk of remote code execution (RCE). The flaw affects versions 0.0.5 through 0.1.15 and has been downloaded more than 437,000 times, making its potential impact significant across the AI and developer communities.
What is mcp-remote?
mcp-remote is a proxy tool designed to facilitate connections between Model Context Protocol (MCP) clients—such as Claude Desktop—and remote MCP servers, even when the client only supports local connections. The tool is commonly integrated into AI and Large Language Model (LLM) workflows, enabling seamless data exchange between local and remote environments.
Details of the Vulnerability
- CVE Identifier: CVE-2025-6514
- Severity: Critical (CVSS 9.6)
- Affected Versions: 0.0.5 to 0.1.15
- Patched Version: 0.1.16
The vulnerability arises during the initial handshake process when mcp-remote connects to a remote MCP server. If the server is malicious or compromised, it can inject arbitrary operating system commands, which are then executed on the client’s machine. This can lead to a full system compromise, especially on Windows platforms.
Platform-Specific Impact
- Windows: Attackers can execute arbitrary OS commands with full parameter control, potentially leading to complete system takeover.
- macOS/Linux: Attackers can execute arbitrary binaries, though with more limited control over command parameters.
Attack Scenarios
The vulnerability can be exploited in two primary ways:
- Malicious MCP Servers: Users who connect to a compromised or intentionally malicious MCP server are at risk of having arbitrary commands executed on their local machine.
- Man-in-the-Middle (MitM) Attacks: If the connection to the MCP server is not secured (e.g., using HTTP instead of HTTPS), attackers on the same network can intercept and manipulate the handshake process to inject malicious commands.
Real-World Impact
This is the first documented instance of a real-world attack vector enabling remote code execution on a client machine simply by connecting to an untrusted MCP server. With over 437,000 downloads of the affected package, the vulnerability poses a significant risk to organizations and individuals leveraging AI tools that depend on mcp-remote.
Mitigation and Recommendations
- Immediate Action: Users are strongly advised to upgrade to
mcp-remoteversion 0.1.16 or later, which addresses the vulnerability by sanitizing handshake data and blocking command injection attempts. - Security Best Practices:
- Only connect to MCP servers you trust.
- Always use secure (HTTPS) connections to prevent MitM attacks.
- Regularly audit and update dependencies for known vulnerabilities.
Summary Table
| Aspect | Details |
|---|---|
| Vulnerability | CVE-2025-6514 |
| Severity | Critical (CVSS 9.6) |
| Affected Versions | 0.0.5 – 0.1.15 |
| Fixed In | 0.1.16 |
| Downloads | 437,000+ |
| Exploit Impact | Remote code execution (full on Windows, limited on macOS/Linux) |
| Recommendation | Upgrade immediately, use secure/trusted MCP servers |
