MCPhantom — Coding Agents Install Deprecated MCP Servers That Will Never Be Patched

When a developer tells a coding agent to "set up a GitHub MCP," the agent has to pick a package.

From real session transcripts, Glow Labs found a pattern they named MCPhantom: the agent picks a server from a repository **that has already been archived and will never receive a fix release** — in 98% of the sessions studied, the package name appears to be filled in from the model's training data rather than from a live search.

A documented case: the agent skips the official GitHub MCP server and picks Anthropic's old reference server.

The pattern appears across Claude Code, Cursor, Codex CLI, and Anthropic/OpenAI/xAI models.

Four vulne…