Vet MCP packages before installing

Malicious postmark-mcp package BCC'd users' emails · Security incident · Hacker News · koisecurity · Sep 2025

Koi Security found an npm MCP server impersonating Postmark that, from one version on, quietly blind-copied every email it sent to an attacker-controlled address.

Lesson

Install MCP servers only from the vendor's official source, pin versions and review updates.

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.

Before I install anything my AI suggests in MCP, help me check it's safe. For the package, extension or MCP server [name]: 1) Check it's the official one (publisher, repo link, download count, how recently it was updated, typo-squatted names). 2) List what permissions or access it gets (files, network, env vars, email). 3) Tell me how to pin the version and review install scripts. 4) Check my project for packages with known security advisories, and tell me how to update them. Don't install or remove anything until I confirm.

Source: Hacker News ↗