mx-chain-go is the official implementation of the MultiversX blockchain protocol, written in golang. When executing a relayed transaction, if the inner transaction failed, it would have increased the inner transaction's sender account nonce. This could have contributed to a limited DoS attack on a targeted account. The fix is a breaking change so a new flag `RelayedNonceFixEnableEpoch` was needed. This was a strict processing issue while validating blocks on a chain. This vulnerability has been patched in version 1.4.17.