A npm package copying the official ‘postmark-mcp’ project on GitHub turned bad with the latest update that added a single line of code to exfiltrate all its users’ email communication.

Published by a legitimate-looking developer, the malicious package was a perfect replica of the authentic one in terms of code and description, appearing as an official port on npm for 15 iterations.

Model Context Protocol (MCP) is an open standard that allows AI assistants to interface with external tools, APIs, and databases in a structured, predefined, and secure manner.