First Malicious MCP in the Wild: The Postmark Backdoor That's Stealing Your Emails | Koi Blog
www.koi.security/blog/postmark-mcp-npm-malicious-backdoor-email-theft
What Jamie wrote
A bad actor takes an open source MCP server, alters it with one line of code to exfiltrate data from the requests, and publishes it under a close enough name. In no time at all a bunch of people have adopted it and are using it with this exfiltration embedded inside it. This isn't a new attack vector. Open source supply chain attacks have existed for a while. Mostly just a caution that this is a easily exploited pattern.