Evmos is the Ethereum Virtual Machine (EVM) Hub on the Cosmos Network. Preliminary checks on actions computed by the clawback vesting accounts are performed in the ante handler. Evmos core, implements two different ante handlers: one for Cosmos transactions and one for Ethereum transactions. Checks performed on the two implementation are different. The vulnerability discovered allowed a clawback account to bypass Cosmos ante handler checks by sending an Ethereum transaction targeting a precompile used to interact with a Cosmos SDK module. This vulnerability is fixed in 18.0.0.
The code does not sufficiently manage its control flow during execution, creating conditions in which the control flow can be modified in unexpected ways.