Submitted by pauliax, also found by 0xsanson, cmichel and shw
The function fulfill first approves the callTo to transfer an amount of toSend tokens and tries to call IFulfillHelper, but if the call fails, it transfers these assets directly. However, in such case the approval is not reset, so a malicous callTo can pull these tokens later:
Tuesday, August 10, 2021
Recommend that approval should be placed inside the try/catch block or approval needs to be reset if the call fails.
LayneHaber (Connext) confirmed and patched:
