RustFS is a distributed object storage system built in Rust. In versions 1.0.0-alpha.13 to 1.0.0-alpha.77, a malformed gRPC GetMetrics request causes get_metrics to unwrap() failed deserialization of metric_type/opts, panicking the handler thread and enabling remote denial of service of the metrics endpoint. This issue has been patched in version 1.0.0-alpha.78.

Affected: crates.io: rustfs

### Summary A malformed gRPC `GetMetrics` request causes `get_metrics` to `unwrap()` failed deserialization of `metric_type`/`opts`, panicking the handler thread and enabling remote denial of service of the metrics endpoint.

### Details - Vulnerable code: `rustfs/src/storage/tonic_service.rs:1775-1782`: - `MetricType` and `CollectMetricsOpts` are deserialized with `Deserialize::deserialize(...).unwrap()` from client-supplied bytes. - Malformed `metric_type`/`opts` (e.g., empty or truncated rmp-serde payloads) trigger `InvalidMarkerRead` and panic. - Reachability: same TCP listener as S3 (default `:9000`); only a static interceptor token `authorization: rustfs rpc` is checked in `server/http.rs:677`. - Impact scope: panic terminates the worker handling the request, causing metrics service interruption and potential process instability.

### PoC

[rustfs-grpc-metrics-invalid-metric-type-panic-poc.tar.gz](https://github.com/user-attachments/files/24038341/rustfs-grpc-metrics-invalid-metric-type-panic-poc.tar.gz)

1) Start RustFS (example local dev): ```bash mkdir -p /tmp/rustfs-data1 /tmp/rustfs-data2 RUSTFS_ACCESS_KEY=devadmin RUSTFS_SECRET_KEY=devadmin \ cargo run --bin rustfs -- --address 0.0.0.0:9000 \ /tmp/rustfs-data1 /tmp/rustfs-data2 ``` 2) From `rustfs-grpc-metrics-invalid-metric-type-panic-poc/`, run: ```bash ENDPOINT=127.0.0.1:9000 make run # or: grpcurl -plaintext \ # -H 'authorization: rustfs rpc' \ # -import-path ../crates/protos/src -proto node.prot…