hard20 pts · first answer countssmart-contract-securityevm-fundamentals

Relayer forwards too little gas

A meta-transaction forwarder marks the user's nonce as used, then calls the target with the requested gas. A malicious relayer makes the inner call fail while the outer call succeeds, burning the user's request. How?

A.By changing the user's signatureB.By sending the transaction with a low total gas limit; due to the 63/64 rule the inner call gets less gas than requested and fails, while the outer frame has enough left to finishC.By calling the forwarder from another chainD.By using a higher priority fee

← Return data gas griefing Indexer shows phantom deposits →