Claude Code has an MCP security problem — and your developers are already using it
Summary
Claude Code, Anthropic's AI coding assistant, stores OAuth tokens (security credentials that prove access permission) in plaintext in a configuration file, and researchers discovered an attack where malicious npm packages (JavaScript libraries) can silently redirect these tokens to attacker-controlled servers before they reach legitimate services like GitHub or Jira. The attack is difficult to detect because the requests appear legitimate in audit logs, and Anthropic has not released a patch despite knowing about the vulnerability since April.
Classification
Affected Vendors
Related Issues
Original source: https://www.csoonline.com/article/4181230/claude-code-has-an-mcp-security-problem-and-your-developers-are-already-using-it.html
First tracked: June 5, 2026 at 08:00 AM
Classified by LLM (prompt v3) · confidence: 92%