CVE-2025-52884

### Impact Prior to 2.1.1 and 2.2.0, the `Steel.validateCommitment` Solidity library function will return `true` for a crafted commitment with a digest value of zero. This violates the semantics of `validateCommitment`, as this does not commitment to a block that is in the current chain. Because the digest is zero, it does not correspond to any block and there exist no known openings. As a result, this commitment will never be produced by a correct zkVM guest using Steel. Leveraging this bug to compromise the soundness of an application using Steel would require a separate bug or misuse of the Steel library, which is expected to be used to validate the root of state opening proofs (e.g. having the guest commit to a digest of zero, or failing to check the zkVM proof). Because this bug does not risk application integrity, correctly written applications are not at risk. ### Fix Please see [#605] for a full description of the bug, and the fix. This fix has been released as part of `risc0-ethereum` [2.1.1] and [2.2.0]. ### Recommended actions Users for the `Steel` Solidity library versions 2.1.0 or earlier should ensure they are using `Steel.validateCommitment` in tandem with zkVM proof verification of a Steel program, as shown in the [ERC-20 counter example][example], and [documentation]. This is the correct usage of Steel, and users following this pattern are not at risk, and do not need to take action. Users not verifying a zkVM proof of a Steel program should update their application to do so, as this is incorrect usage of Steel. ### Credit A thank you to Daniel526 on HackenProof for reporting this issue [#605]: https://github.com/risc0/risc0-ethereum/pull/605 [example]: https://github.com/risc0/risc0-ethereum/blob/ff0cb9253a87945b653b825711b8b5075f8b7545/examples/erc20-counter/contracts/src/Counter.sol#L56-L63 [documentation]: https://docs.beboundless.xyz/developers/steel/how-it-works#verifying-the-proof-onchain [2.1.1]: https://github.com/risc0/risc0-ethereum/releases/tag/v2.1.1 [2.2.0]: https://github.com/risc0/risc0-ethereum/releases/tag/v2.2.0