Metadata: require issuer to match the URL it was fetched from#17
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rohanharikr wants to merge 1 commit into
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Metadata: require issuer to match the URL it was fetched from#17rohanharikr wants to merge 1 commit into
rohanharikr wants to merge 1 commit into
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Adds a normative MUST that verifiers check metadata.issuer matches the
URL they retrieved the document from (less the /.well-known/{dwk}
suffix). Rejects mismatch.
Prevents host-poisoned metadata: an attacker hosting metadata at one
domain claiming an issuer of another. Parallels RFC 8414's analogous
requirement for OAuth Authorization Server Metadata.
Closes dickhardt#12
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Closes #12
Adds a normative MUST in the Metadata Documents section: when fetching a metadata document, implementations MUST verify that
issuermatches the URL the document was retrieved from (less the/.well-known/{dwk}suffix). Mismatch → reject.Why
Without this check, a "host-poisoned metadata" attack is possible against permissive verifiers — an attacker hosts a metadata document at their own domain claiming a different
issuer, and a verifier that followsjwks_urifrom such a document could end up trusting attacker-controlled keys for tokens claiming the impersonated issuer.RFC 8414 (OAuth Authorization Server Metadata) makes the analogous check normative for OAuth. Bringing the AAuth metadata spec into alignment.
Diff scope
Two paragraphs added at the top of
## Metadata Documents. Applies uniformly across agent server, resource, PS, and AS metadata since they all share the same well-known fetch pattern.