Submitted by 3docSec, also found by Fulum, Limbooo, DanielArmstrong, T1MOH, and Krace
The V3Proxy swapTokensForExactETH function swaps an unspecified amount of a given ERC-20 for a specified amount of the native currency. After the swap happens, however, the difference between the amount taken from the caller (amountInMax) and the actual swapped amount (amounts[0]) is not given back to the caller and remains locked in the contract.
Any user of the swapTokensForExactETH will always pay amountInMax for swaps even if part of it was not used for the swap. This part is lost, locked in the V3Proxy contract.
Send back the excess tokens:
Keref (Good Entry) confirmed and commented:
Good Entry Mitigated:
Status: Mitigation confirmed. Full details in reports from kutugu, xuwinnie and 3docSec.
