MinIO is a High Performance Object Storage released under GNU Affero General Public License v3.0. The signature component of the authorization may be invalid, which would mean that as a client you can use any arbitrary secret to upload objects given the user already has prior WRITE permissions on the bucket. Prior knowledge of access-key, and bucket name this user might have access to - and an access-key with a WRITE permissions is necessary. However with relevant information in place, uploading random objects to buckets is trivial and easy via curl. This issue is fixed in RELEASE.2025-04-03T14-56-28Z.

MinIO performs incomplete signature validation for unsigned-trailer uploads