Submitted by WatchPug, also found by Jujic and hack3r-0m
https://github.com/code-423n4/2021-11-streaming/blob/56d81204a00fc949d29ddd277169690318b36821/Streaming/src/Locke.sol#L733-L735
When an incentiveToken is claimed after endStream, incentives[who] will be 0 for that incentiveToken.
If the protocol gov is malicious or compromised, they can call arbitraryCall() with the address of the incentiveToken as who and transferFrom() as calldata and steal all the incentiveToken in the victims wallet balance up to the allowance amount.
The compromised protocol gov can call arbitraryCall() and steal all the USDC in Alices wallet balance.
Consider adding a mapping: isIncentiveToken, setting isIncentiveToken[incentiveToken] = true in createIncentive(), and require(!isIncentiveToken[who], ...) in arbitraryCall().
brockelmore (Streaming Protocol) confirmed
