Root + Impact:

Description

• In normal protocol behavior, a user should not be able to fill an expired order. The buyOrder function includes a deadlineTimestamp check to prevent this.

• Because the contract relies on block.timestamp, miners can shift the time slightly (up to ~15 seconds). This lets them fill orders that should have already expired, breaking the expected behavior of the protocol.

Risk

Likelihood:

• Miners can adjust block.timestamp slightly to favor their own or selected transactions.

• This becomes especially relevant when orders are filled close to the expiration boundary, which is common in tight trading scenarios or sniping attempts.

Impact:

• Orders may be filled even though they have technically expired.

• This breaks time-based guarantees and can be exploited in race conditions.

Proof of Concept:

No PoC required, as the vulnerability is due to protocol-level miner behavior affecting block.timestamp.

Recommended Mitigation

Use Chainlink Automation (or other off-chain services) to flag expired orders based on timestamp and mark them inactive, removing reliance on block.timestamp within user transactions.