SeaweedFS’s VolumeServer.FetchAndWriteNeedle function accepts a remote endpoint provided by the caller and forwards the request to an external host, then writes the response back into a storage needle. The RPC performs no authentication and provides no validation of the target, enabling an unauthenticated server‑side request forgery that can reach arbitrary hosts, including loopback, link‑local ranges, RFC 1918 addresses and cloud metadata endpoints such as 169.254.169.254. The resulting SSRF can expose instance metadata, IAM credentials and otherwise hidden internal services, allowing an attacker to gather sensitive information from within the network.

The flaw is present in all SeaweedFS releases prior to version 4.24, including 4.23 and earlier. SeaweedFS runs a gRPC server on the volume‑server plane that, by default, is unauthenticated. Any deployment of seaweedfs:seaweedfs that has not applied the 4.24 update and that exposes the gRPC port to external traffic is affected.

The vulnerability scores a CVSS of 9.3, indicating a severe risk if exploited. The EPSS score is <1%, suggesting a low but non‑zero probability of exploitation in the observable threat landscape, and the vulnerability is not yet listed in the CISA KEV catalog. The attack requires the ability to reach the volume‑server gRPC port; once reached, the attacker can direct requests to any target, including cloud metadata services, and read back the response payload. This capability provides a wide attack surface for credential theft and internal reconnaissance.