The vulnerability involves incomplete signature validation for unsigned-trailer uploads in MinIO. The key vulnerable functions identified are:
- newUnsignedV4ChunkedReader - This was the main function processing unsigned trailer uploads without proper signature validation (added in the patch).
- isRequestUnsignedTrailerV4 - Its validation was too permissive, allowing unsigned uploads to proceed.
- authenticateRequest - Needed to explicitly reject these auth types.
The patches show these functions were modified to add proper validation, indicating they were involved in the vulnerability. The test case (TestUnsignedCVE) demonstrates how these functions would be called during exploitation, showing they would appear in runtime profiling when the vulnerability is triggered.