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…ting Previously, when an attestation config had a bundle_url but no publishers, the identity check loop was empty and verification would always succeed. Even with publishers specified, the code relied solely on sigstore-verify's internal subject check without an explicit artifact-to-subject verification. This adds an explicit `verify_artifact_subject()` check that runs before identity verification: it computes the artifact's SHA-256 digest and confirms it matches at least one subject in the attestation's in-toto statement. This prevents accepting an attestation for a different file (e.g., from a different release or a completely unrelated artifact). This is analogous to CVE-2026-31830 in sigstore-ruby where the subject digest check result was silently ignored. https://claude.ai/code/session_01SkB2VgUFbUgew9UG1WqNet
wolfv
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Summary
This PR fixes the experimental attestation verification process that ensures the downloaded artifact's SHA-256 digest matches at least one subject in the in-toto statement of the attestation bundle. This prevents accepting attestations for different artifacts (e.g., from different releases).