This release includes 2 security fixes for security teams reviewing exposed deployments.
Topics
Affected surfaces
Summary
AI summaryRemoved request‑scoped TFE_TOKEN, Authorization, and TFE_ADDRESS passthrough to prevent confused‑deputy attacks.
Full changelog
Changelog
All notable changes to tfmcp are documented in this file.
0.2.1 - 2026-07-26
v0.2.1 consolidates the completed v0.2.x work into one stable release while
preserving tfmcp's local-first Terraform workflows.
Added
- Public and private Terraform Registry tools, including the
registry-privatetoolset and HashiCorp-compatible provider, module, and
policy aliases. - Local project inspection, Terraform entrypoint detection, plan review,
provider lockfile checks, module health analysis, and state safety checks. - HCP Terraform and Terraform Enterprise read APIs for organizations,
projects, workspaces, runs, plans, applies, variables, policy sets, variable
sets, tags, stacks, and private Registry content. - Explicitly gated HCP/TFE operations, including
attach_variable_set_to_workspaces; operations remain disabled until
ENABLE_TF_OPERATIONS=true. - Streamable HTTP transport with loopback defaults, health and metrics
endpoints, stateful/stateless sessions, Host and Origin validation, rate
limits, TLS file wiring, organization allowlists, and heartbeat control. - MCP resources including
/terraform/providers/{namespace}/name/{name}/version/{version}.
Changed
- Updated the tested and containerized Terraform baseline to 1.15.8.
- Updated the declared RMCP SDK baseline to 1.8.
- Set and continuously test the Rust 1.88 MSRV; Docker builds use the same
locked dependency graph instead of an unpinned nightly toolchain. - Split MCP protocol/analysis concerns and TFE client operations, configuration,
encoding, and response handling into narrower modules. - Consolidated Terraform formatting and refresh wrappers around explicit mode
enums to remove duplicated control flow. - Added
cargo couplingandsimilarity-rsarchitecture gates to CI and the
release process.
Security
- Streamable HTTP validates request origins in every CORS mode and uses
loopback-only origins by default. - Removed request-scoped
TFE_TOKEN,Authorization, andTFE_ADDRESS
passthrough. Downstream HCP/TFE calls use only server-configured credentials,
preventing confused-deputy and token-passthrough behavior. - HCP/TFE writes, local dangerous operations, and auto-approve remain separate,
fail-closed gates. - Organization allowlists reject account-wide and ID-scoped requests whose
ownership cannot be verified. - TFE response bodies, HTTP metric routes, and rate-limit session state are
bounded; sensitive credentials are not returned by status APIs.
HashiCorp v1.0.x Compatibility
The compatible surface includes get_plan_json_output, get_apply_logs,
list_variable_sets, attach_variable_set_to_workspaces,
read_workspace_tags, and list_stacks. tfmcp also retains capabilities
beyond API mirroring: local Terraform CLI workflows, entrypoint detection,
module health analysis, state safety checks, and local dangerous-operation gates.
Breaking Changes
- Removed request-scoped `TFE_TOKEN`, `Authorization`, and `TFE_ADDRESS` passthrough; downstream HCP/TFE calls now use only server‑configured credentials.
Security Fixes
- Streamable HTTP transport now validates request origins in every CORS mode and defaults to loopback‑only origins.
- Removed request‑scoped `TFE_TOKEN`, `Authorization`, and `TFE_ADDRESS` passthrough, preventing confused‑deputy and token‑passthrough behavior.
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About nwiizo/tfmcp
Terraform Model Context Protocol (MCP) Tool - An experimental CLI tool that enables AI assistants to manage and operate Terraform environments. Supports reading Terraform configurations, analyzing plans, applying configurations, and managing state with Claude Desktop integration. ⚡
Related context
Beta — feedback welcome: [email protected]