Fake postmark-mcp npm package secretly copied users' emails to an outside server
An npm package named postmark-mcp posed as an MCP server for the Postmark email service. Starting with version 1.0.16, published on September 17, 2025, it added a hidden BCC that sent copies of users' emails to an outside server. Postmark says it never published or authorized the package. The package was pulled from npm on September 25, 2025, and Postmark told users to remove it and rotate credentials.
Sources
- Primary: https://postmarkapp.com/blog/information-regarding-malicious-postmark-mcp-package
- Upstream: Editorial
- Entered by the cybermap.lol editors, with sources on the entry
Defenses for this class of incident
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