Code & Chain · Signal Desk

SkillLeak Vulnerability Revealed: MCP Skills Can Steal Browser-Stored Credentials

Original sourceXygeni

Summary

Security research found that the MCP skill package local-browser-test can decrypt credentials stored in Chrome/Edge browsers (using DPAPI and AES-256-GCM) and transmit decrypted credentials to a remote server. This risk requires the developer to actively execute the skill, but highlights the need f…

Key points

  • As MCP skills become more prevalent, this vulnerability underscores the need for security vetting of third-party skills.
  • MCP skills could become a new vector for credential theft; developers must audit the source and behavior of skills.
  • Developers should avoid executing unknown MCP skills and scan skill code for access to local credential stores.
  • Similar to npm package supply chain attacks, but the attack surface extends to the AI agent skill layer.

Editorial note

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