The mintToken function of a smart contract implementation for ETHEREUMBLACK (ETCBK), an Ethereum token, has an integer overflow that allows the owner of the contract to set the balance of an arbitrary user to any value.

The sell function of a smart contract implementation for ETHEREUMBLACK (ETCBK), an Ethereum token, has an integer overflow in which "amount * sellPrice" can be zero, consequently reducing a seller's assets.