Ethereum’s proposed safety checks could still let a bad trade through

Ethereum's Proposed Safety Checks May Not Prevent Losses

Proposed Safety Checks May Not Prevent Losses

The Ethereum Foundation has proposed a new safety check mechanism, EIP-7906, which aims to provide more flexibility and protection for users. However, the system relies on wallet and protocol configuration to enforce rules, which can be weakened by permissive minimum values.

Current Limitations

Ethereum already enforces some financial limits, such as Uniswap v3's swap router, which rejects exact-input swaps when the amount received is below the minimum receipt. However, this system has its limitations, as it only checks for minimum receipt and does not consider the overall outcome of the trade.

Proposed Solution

EIP-7906 proposes a broader view of the transaction's effects, building on EIP-8141's ordered frames. It adds read-only POST_TX frames at the end, which inspect the resulting state and reject execution that violates its rule. The proposed instructions divide that work into three operations: TXTRACE, TXDIFF, and EVENTDATACOPY.

Implementation and Security

The proposal does not require every transaction to contain an assertion, and an account relying on one must configure its validation logic to require the specific POST_TX frame without a bypass. A protocol has a related obligation to enforce the exact required assertion, rejecting ordinary transactions and frame transactions with missing or incorrect checks. The proposed solver guarantee applies to one transaction on one network, and the policy must also survive the actions it is supposed to judge.