Wasmi is an efficient and lightweight WebAssembly interpreter with a focus on constrained and embedded systems. In the WASMI Interpreter, an Out-of-bounds Buffer Write will arise if the host calls or resumes a Wasm function with more parameters than the default limit (128), as it will surpass the stack value. This doesn’t affect calls from Wasm to Wasm, only from host to Wasm. This vulnerability was patched in version 0.31.1.

Affected: crates.io: wasmi

### Summary

In the WASMI Interpreter, an [Out-of-bounds Buffer Write](https://cwe.mitre.org/data/definitions/787.html) will arise arise if the host calls or resumes a Wasm function with more parameters than the default limit (128), as it will surpass the stack value. This doesn’t affect calls from Wasm to Wasm, only from host to Wasm.

### Impact

After conducting an analysis of the dependent Polkadot systems of `wasmi`: [Pallet Contracts](https://github.com/paritytech/polkadot-sdk/tree/master/substrate/frame/contracts), [Parity Signer](https://github.com/paritytech/parity-signer), and [Smoldot](https://github.com/smol-dot/smoldot), we have found that none on those systems have been affected by the issue as they are calling host to Wasm function with a small limited amount of parameters always.

### Mitigations

If you are using `wasmi` betwen version 0.15.0 and 0.31.0, please update it to the [0.31.1](https://github.com/paritytech/wasmi/releases/tag/v0.31.1) patch release that we just published.

### Workarounds

Ensure no more than 128 parameters can be pass in a call from the host to a Wasm function.

### References

Patch PR: <PR>

### Special thanks

Special thanks to Stellar Development Foundation for reporting this security vulnerability.