Submitted by unforgiven
PromiseRouter.sol#L226-L262
process() in PromiseRouter is used for process stored callback function and anyone calls it gets callbackFee and it calls callback() function of callbackAddress. but attacker set a callbackAddress that reverts on callback() and cause process()  caller griefing. attacker can perform this buy front running or complex logic.
This is process() code:
As you can see it calls ICallback(callbackAddress).callback(transferId, _msg.returnSuccess(), _msg.returnData()); and if that call reverts then whole transaction would revert. so attacker can setup callbackAddress that revert and the caller of process() wouldnt get any fee and lose gas.
VIM
Change the code so it wont revert if call to callbackAddress reverts.
jakekidd (Connext) confirmed, but disagreed with severity
jakekidd (Connext) commented:
LayneHaber (Connext) changed to acknowledged and commented:
0xleastwood (judge) commented:
