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mcp-runtime-authz is a firewall between an MCP client (Claude Code, Claude Desktop, Cursor) and the MCP servers it uses. It checks every tool call before it runs.
This release changes no policies and no command-line behaviour. It tests claims that were previously only stated, and documents the security model.
Tested, not just claimed
- Fail-closed audit log. A new test puts the audit log on
/dev/full, a device where every write fails, and checks that allowed and escalated calls are refused and never run. - Published results. A new test runs the full evaluation and fails if the numbers in
report/findings.mdstop holding: 7/7 attacks blocked, 0/6 false positives, and exactly two rules whose removal lets an attack through. - Coverage. CI measures line coverage (86%) and fails below 80%.
- Reproducible builds. CI builds the release binary twice from clean and fails unless the two are bit-for-bit identical.
Hardening
- Release builds keep integer overflow checks.
- The decision path keeps the session's history and taint data even if an internal lock is poisoned, instead of dropping them, which would have failed open. This could not happen in practice; the fix is defensive.
Docs
- Security model and assurance case: what the guard guarantees and how each guarantee is tested, what it does not promise, the threat model, trust boundaries, and a table of common weaknesses (CWE) and their countermeasures.
- Architecture, governance, code of conduct, roadmap, and a reference for every command and file format.
- The project holds the OpenSSF Best Practices passing badge.
No vulnerabilities were fixed in this release.
Verify a download:
gh attestation verify <archive> --repo Wazza0/mcp-runtime-authz