GHSA-gxw4-4fc5-9gr5

Описание

Summary

A command injection vulnerability exists in the figma-developer-mcp MCP Server. The vulnerability is caused by the unsanitized use of input parameters within a call to child_process.exec, enabling an attacker to inject arbitrary system commands. Successful exploitation can lead to remote code execution under the server process's privileges.

The server constructs and executes shell commands using unvalidated user input directly within command-line strings. This introduces the possibility of shell metacharacter injection (|, >, &&, etc.).

Details

The MCP Server exposes tools to perform several figma operations. An MCP Client can be instructed to execute additional actions for example via indirect prompt injection that can lead to command injection by calling vulnerable tools with malicious inputs. Below some example of vulnerable code and different ways to test this vulnerability.

Vulnerable code

The following snippet illustrates the vulnerable code pattern used in the MCP Server’s tooling.

Using MCP Client IDE

1. Verify the file /tmp/TEST1 does not exist:

2. setup your client IDE

4. open the chat and enter the following prompt:

5. run the get_figma_data tool

6. Confirm that the injected command executed:

Using MCP Inspector

1. Open the MCP Inspector:

2. In MCP Inspector:

   • set transport type: STDIO
   • set the command to npx
   • set the arguments to figma-developer-mcp --stdio
   • set the FIGMA_API_KEY env variable (i.e TEST)
   • click Connect
   • go to the Tools tab and click List Tools
   • select the get_figma_data tool

3. Verify the file /tmp/TEST does not exist:

5. In the fileKey field, input:

• Click Run Tool

6. Observe the request being sent:

Output:

Logs:

7. Confirm that the injected command executed:

Remediation

To mitigate this vulnerability, I suggest to avoid using child_process.exec with untrusted input. Instead, use a safer API such as child_process.execFile, which allows you to pass arguments as a separate array — avoiding shell interpretation entirely.

NOTE: This mitigation—and others like input validation—have been implemented in versions 0.6.3 and above. To fix the issue, make sure you're using a version >=0.6.3.

Impact

Command Injection / Remote Code Execution (RCE)