With the account_contract.cairos execute_from_outside function, callers submit a calldata blob of calldata_len length, out of which the transaction data is extracted by selecting [call_array].data_len bytes starting from position [call_array].data_offset.
Within the logic that makes this extraction, there is no check that [call_array].data_offset + [call_array].data_len fits within calldata_len, effectively allowing for the submission of transactions that pass or fail validation depending on whats allocated out of the boundaries of the input data.
Consider adding a boundary check to enforce [call_array].data_offset + [call_array].data_len < calldata_len.
Similar lack of validation for non-critical variables can be found in the actual length of the signature array vs signature_len, the actual length of the call_array vs call_array_len, as well as in eth_transactions::parse_access_list(), where the parsing of address_item misses a check that address_item.data_len = 20, that the access_list.data_len = 2 (spec in the python snippet here).
Kakarot mitigated:
Status: Mitigation confirmed.
