GHSA-7mm3-vfg8-7rg6: Babylon Finality Provider `MsgCommitPubRandList` replay attack

A high vulnerability exists in the Babylon protocol’s x/finality module due to a lack of domain separation in signed messages, combined with insufficient validation in the MsgCommitPubRandList handler. Specifically, the handler does not enforce that the submitted Commitment field is 32 bytes long. This allows an attacker to replay a signature originally generated for a different message (e.g., a Proof-of-Possession in MsgCreateFinalityProvider) as a MsgCommitPubRandList. By crafting the message parameters, an attacker can use the typically 20-byte address bytes (from the PoP context) to form the StartHeight, NumPubRand, and a shorter-than-expected Commitment (e.g., 4 bytes). The replayed signature will pass verification for this crafted message, leading to the injection of an invalid PubRand commitment.