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Postmark-mcp npm backdoor copying outbound emails

Malware Activity
First reported
Last updated
Happening score
H score 28
1 unique sources, 1 articles

Summary

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The postmark-mcp npm package was found to include a backdoor that silently copied outbound emails, creating a supply-chain risk for users of the MCP server. The malicious code appeared in version 1.0.16 and forwarded messages to phan@giftshop[.]club. The package was later removed from npm after discovery. Anyone who installed it may have exposed sensitive mail content handled by the server.

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Open Happening

Timeline

  3. 29.09.2025 11:36 2 articles · 9mo ago

    Koi Security identifies the malicious MCP server

    Initial Disclosure

    Koi Security identified postmark-mcp as the first real-world malicious MCP server and warned that it had been silently copying every outbound email to phan@giftshop[.]club, exposing sensitive communications and prompting users to remove the package and review BCC traffic.

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