figma-developer-mcp vulnerable to command injection in get_figma_data tool

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.

// https://github.com/GLips/Figma-Context-MCP/blob/v0.5.2/src/utils/fetch-with-retry.ts#L35

export async function fetchWithRetry(url: string, options: RequestOptions = {}): Promise {
  try {
    const response = await fetch(url, options);
    ...
  } catch (fetchError: any) {
	...
    const curlHeaders = formatHeadersForCurl(options.headers);
    ...
    const curlCommand = `curl -s -S --fail-with-body -L ${curlHeaders.join(" ")} "${url}"`; //<--…