Submitted by evan, also found by HollaDieWaldfee
By creating a drip that ends after the current cycle but before its creation time and immediately removing it, the sender doesnt have to put in any assets but the receiver can still squeeze this drip.
By setting a receiver that the sender controls, the sender can drain an arbitrary asset from the contract.
Let the cycle length be 10 seconds. By i-th second I mean the i-th second of the cycle.
At the 5th second, sender creates a drip that starts at 0th second and lasts for 2 seconds.
At the 6th second, sender removes this drip.
https://github.com/code-423n4/2023-01-drips/blob/main/src/Drips.sol#L569
Since the drip ends before it was created, the dripped amount is 0, so the sender can retrieve their full balance.
https://github.com/code-423n4/2023-01-drips/blob/main/src/Drips.sol#L425-L430 
https://github.com/code-423n4/2023-01-drips/blob/main/src/Drips.sol#L490-L496
Now the receiver squeezes from this drip. 
SqueezeStartCap = \_currCycleStart() = 0th second, squeezeEndCap = 6th second, so the receiver can still squeeze out the full amount even though the sender has withdrawn all of his balance.
Please add the following test to DripsHub.t.sol. It verifies that the sender has retrieved all of his assets but the receiver can still squeeze.
VS Code, Foundry
https://github.com/code-423n4/2023-01-drips/blob/main/src/Drips.sol#L426
One potential solution is to add an additional check after this line. Something along the lines of:
if (squeezeStartCap < drips.updateTime) squeezeStartCap = drips.updateTime;
CodeSandwich (Drips) confirmed and commented:
Alex the Entreprenerd (judge) commented:
