Submitted by jonah1005
The lptoken minted by the Pool contract is actually the mix of two types of tokens. One is the original lptokens user get by calling addForMember. This lpToken is similar to lp of Uniswap, Crv, Sushi,  etc. The other one is the debt-lp token the Synth contract will get when the user calls mintSynth. The Synth contract can only withdraw Sparta for burning debt-lp. Mixing two types of lp would raise several issues.
LP user would not get their fair share when they burn the lP.
The pool would end up left behind a lot of token B in the Pool while theres no lp holder.
I would say this is a high-risk vulnerability since it pauses unspoken risks and losses for all users (all the time)
The logic of burn original lp and burn debt-lp.
I do not know whether this is the teams design choice or its composite with a series of bugs. If this is the original design, I do not come up with a fix. Its a bit similar to the impermanent loss. However, the loss would be left behind in the Pool. This is more complicated and maybe worse than the impermanent loss. If this is the design choice, I think its worth emphasize and explain to the users.
verifyfirst (Spartan) confirmed and disagreed with severity:
SamusElderg (Spartan) commented:
