GHSA-2557-x9mg-76w8 ASA-2024-002: Default `PrepareProposalHandler` may produce invalid proposals when used with default `SenderNonceMempool`

• Go github.com/cosmos/cosmos-sdk: >= 0.50.0, < 0.50.4 → fixed in 0.50.4 • Go github.com/cosmos/cosmos-sdk: < 0.47.9 → fixed in 0.47.9

ASA-2024-002: Default `PrepareProposalHandler` may produce invalid proposals when used with default `SenderNonceMempool` Component: Cosmos SDK Criticality: Medium Affected Versions: Cosmos SDK versions <= 0.50.3; <= 0.47.8 Affected Users: Chain developers, Validator and Node operators Impact: Denial of Service Summary When using the default `PrepareProposalHandler` and the default `SenderNonceMempool`, an issue was identified which may allow invalid blocks to be proposed when a single sender includes multiple transactions with non-sequential sequence numbers in certain conditions. If this state is reached, it can lead to a reduction in block production for a network. Next Steps for Impacted Parties If you are a chain developer on an affected version of the Cosmos SDK, it is advised to update to the latest available version of the Cosmos SDK for your project. Once a patched version is available, it is recommended that network operators upgrade. A Github Security Advisory for this issue is available in the Cosmos-SDK repository. For more information about Cosmos SDK, see https://docs.cosmos.network/. This issue was found by KonradStaniec, gitferry, SebastianElvis, and vitsalis who reported it to the Cosmos Bug Bounty Program on HackerOne on January 16, 2024. If you believe you have found a bug in the Interchain Stack or would like to contribute to the program by reporting a bug, please see https://hackerone.com/cosmos.