fastmcp Releases

This release focuses on bug fixes to improve stability in authentication, edge session handling, and resource management. It ensures DCR clients are properly persisted and session initialization is robust.

Sep 9, 2026

A bug fix release focused on OpenAPI resource templates, addressing an issue where repeated path parameters were not being replaced correctly.

Sep 9, 2026

A maintenance release focusing on OpenAPI benchmarks, involving the re-pinning of Twilio and PostHog spec hashes and fixing path parameter repetition.

Sep 9, 2026

This release fixes a bug in the tools module by ensuring streamContent is routed through a request-scoped notifier.

Sep 7, 2026

This release resolves an issue where custom route streams over HTTP were failing to settle properly.

Sep 7, 2026

This release fixes a bug in the progress module by ensuring tool progress is routed through a request-scoped notifier.

Sep 7, 2026

Version 4.20.3 addresses a specific issue regarding the preservation of multiple custom route cookies within the HTTP module.

Sep 6, 2026

This release focuses on dependency maintenance and internal fixes. It upgrades the mcp-proxy library to version 6.7.13 and removes a specific workaround for the WWW-Authenticate header.

Sep 4, 2026

Fixed a bug in the HTTP module where the WWW-Authenticate header was not emitted correctly during authentication failures.

Sep 4, 2026

This release introduces new functionality to the OpenAPI integration, specifically wiring up output schema and structured content handling with various serialization styles.

Sep 4, 2026

This is a maintenance release focused on bug fixes related to authentication and HTTP stream handling to ensure proper resource cleanup and authentication efficiency.

Sep 4, 2026

This release focuses on improvements to the OpenAPI integration, specifically fixing form-urlencoded request bodies and introducing a GET-to-resource mapping feature.

Sep 1, 2026

This release introduces a new `fromOpenAPI()` converter designed to work with OpenAPI 3.x specifications, allowing users to easily import REST API schemas. It also includes a real-world benchmark suite to validate the performance and accuracy of the new converter.

Sep 1, 2026

This release addresses a security requirement in the OAuth implementation by mandating S256 PKCE for CIMD clients. It resolves issue #348 to ensure better security compliance.

Aug 31, 2026

Adds support for Client ID Metadata Documents (CIMD) within the OAuthProxy module.

Aug 31, 2026

A maintenance release addressing a security vulnerability and improving prompt handling logic.

Aug 31, 2026

This release focuses on stabilizing data handling and caching mechanisms to ensure data integrity across JSON pointers and discovery fetches.

Aug 29, 2026

Improves security and session lifecycle management by obscuring sensitive identifiers during rejections and ensuring proper invalidation upon closure.

Aug 27, 2026

Enhances session reliability by making teardown processes fail-safe and preventing unauthorized reinitialization attempts.

Aug 27, 2026

Fixes a resource leak by ensuring stream pumping stops immediately when the client disconnects to prevent unnecessary resource consumption.

Aug 26, 2026