Description
hyper-mcp through 0.8.3 contains a signature verification bypass vulnerability in load_wasm in src/wasm/oci.rs that verifies the Cosign signature of a separately resolved tag rather than the loaded manifest. Attackers controlling registry responses for the tag can serve an unsigned malicious manifest to the loader and a signed one to Cosign, executing unsigned WebAssembly plugins with configured host capabilities.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| hyper-mcp-rs | hyper-mcp | ≤ 0.8.3 | — |
References
- https://hackmd.io/@1ExmmukzRMWN7B4gQ4W-4Q/hyper-mcp-oci-signature-manifest-toctou third-party-advisory
- https://github.com/hyper-mcp-rs/hyper-mcp/blob/v0.8.3/src/wasm/oci.rs#L79-L148 technical-description
- https://github.com/hyper-mcp-rs/hyper-mcp/blob/v0.8.3/src/wasm/oci.rs#L193-L224 technical-description
- https://github.com/hyper-mcp-rs/hyper-mcp product
- VulnCheck Advisory: hyper-mcp through 0.8.3 OCI Plugin Signature Verification TOCTOU Race Condition third-party-advisory