Security: require 'audience' for jwt auth (RFC 8707 confused-deputy defense)#5
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… defense) fastmcp's JWTVerifier accepts audience=None and then SKIPS audience validation. mk_auth_provider passed the caller's audience straight through, so omitting it silently disabled the RFC 8707 audience binding — a token minted for another service could be replayed against this server (confused-deputy). For a helper whose whole job is to build a SECURE resource server, that fail-open default is wrong: now 'audience' is required for type='jwt' and a missing one raises a clear error. Also sync pyproject version to 0.1.5 (PyPI already has 0.1.5 from the http merge; the wads auto-bump never pushed the bump back) so the next publish is 0.1.6. Found by an adversarial security review of the remote-connector work. +1 test.
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What
fastmcp'sJWTVerifieracceptsaudience=Noneand then skips audience validation.mk_auth_providerpassed the caller'saudiencestraight through, so omitting it silently disabled the RFC 8707 audience binding — a token minted for another service could be replayed against this server (confused-deputy).For a helper whose entire purpose is to build a secure OAuth 2.1 resource server, that fail-open default is wrong. Now
audienceis required fortype='jwt'; a missing one raises a clear, educational error.Also
Syncs
pyproject.tomlversion0.1.4 → 0.1.5— PyPI already has 0.1.5 (published when the http feature merged), but the wads auto-bump never pushed the version bump back to main (the known push-back desync). Without this, the next merge would try to re-publish 0.1.5 and fail; with it, the bump lands on 0.1.6.Why now
Found by an adversarial security review of coact's remote-connector work (which builds on this layer). coact always supplies an audience, so it is unaffected — this hardens the helper against any caller.
Tests
+1 regression test (
test_missing_audience_raises); full suite 20 passed; ruff clean.