Submitted by jayjonah8, also found by dalgarim and kenzo
In StabilityPool.sol, the receiveCollateral() function should be called by ActivePool per comments,  but anyone can call it passing in _tokens and _amounts args to update stability pool balances.
https://github.com/code-423n4/2021-12-yetifinance/blob/main/packages/contracts/contracts/StabilityPool.sol#L1143
Allow only the ActivePool to call the receiveCollateral() function:
require(msg.sender = address(active pool address), Can only be called by ActivePool)
kingyetifinance(Yeti finance) confirmed:
0xtruco (Yeti finance) commented:
