ContextCrush Flaw in Context7 MCP Server
Noma Labs discovered the ContextCrush vulnerability in Context7, a registry that delivers coding documentation to AI assistants via an MCP server. Attackers manipulated the platform's Custom Rules feature to plant malicious instructions. When an AI coding assistant (like Cursor or Windsurf) queried the documentation, it ingested the poisoned rules via the trusted MCP channel and autonomously executed harmful actions, such as stealing .env files.
Widespread credential theft and data exfiltration via third-party documentation poisoning.