Limit what a GitHub MCP token can reach
GitHub MCP exploited to leak private repositories · Security incident · Hacker News · invariantlabs · May 2025
Invariant Labs showed a malicious issue in a public repo could make an agent using the GitHub MCP server copy data from the user's private repos into a public pull request.
Lesson
Scope agent tokens to a single repo and require approval for tool calls that write to public places.
Fix prompt
Copy this into your own AI tool (Cursor, Lovable, Claude Code, Bolt…). It's general guidance written by us. Review what the AI suggests before applying it.
I use GitHub MCP, which can read web pages, files, emails or tool output. Help me reduce the risk of prompt injection (hidden instructions in content the AI reads). 1) List what my setup can access (files, terminal, browser, MCP servers, email, databases) and what it can do without asking me. 2) Point out the riskiest combinations, e.g. reading untrusted content while also having access to secrets or the ability to send data out. 3) Suggest concrete settings: require approval for commands and network calls, remove MCP servers I don't need, use read-only tokens, and keep the tool updated. 4) Give me a short checklist to follow before opening untrusted repos or documents. Don't change anything until I've approved your plan. Never ask me to paste API keys, passwords or .env contents; tell me where to check them myself.
Source: Hacker News ↗