SeaweedFS is a distributed storage system. Prior to 4.24, VolumeServer.FetchAndWriteNeedle in weed/server/volume_grpc_remote.go fetches a caller-supplied remote endpoint through weed/remote_storage/s3/s3_storage_client.go and writes the response into a needle. The RPC performs no authentication and no target validation, allowing anyone who can reach a volume server's gRPC port to cause requests to arbitrary hosts, including loopback, link-local, RFC 1918, and cloud metadata endpoints such as 169.254.169.254, and read the response. On cloud deployments, this can disclose instance metadata and IAM credentials and reach otherwise unexposed internal services. The volume server gRPC plane is unauthenticated by default, and configuring documented JWT signing keys does not protect this RPC. This issue is fixed in version 4.24.