FastMCP

v4.7.2 Bugfix

This release fixes issues for SREs watching stability and regressions.

Published 9d MCP Developer Tools

✓ No known CVEs patched

✓ No known CVEs patched in this version

Topics

mcp sse

Affected surfaces

auth

Summary

AI summary

Authentication failures now return a 401 status code instead of relying on error-message heuristics.

Type	Severity	Summary	CVE
Bugfix	Medium	Returns 401 for authentication failures instead of using error-message heuristics. Returns 401 for authentication failures instead of using error-message heuristics. Source: llm_adapter@2026-07-18 Confidence: low	—

Full changelog

return 401 for authentication failures instead of relying on error-message heuristics (#288) (7077962), closes #180 #createUnauthorizedResponse

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About FastMCP

A high-level framework for building MCP servers in TypeScript