FIRST MALICIOUS MCP IN THE WILD: THE POSTMARK BACKDOOR THAT'S STEALING YOUR EMAILS

Summary from the TLDR InfoSec newsletter

MCP servers, designed to help AI assistants automate tasks like sending emails, can pose significant security risks if abused. Recently, a popular npm package called postmark-mcp was discovered to be exfiltrating emails—including sensitive content like password resets and confidential memos—to a remote server controlled by its developer. The backdoor was introduced in a single line of code within an otherwise trustworthy tool, highlighting how quickly legitimate infrastructure can become compromised.