Summary

Tokens whose code and logic can be changed in future can break the protocol and lock user funds.

Vulnerability Details

For a token like TUSD (supported by Chainlink TUSD/USD price feed), which has a proxy and implementation contract, if the implementation behind the proxy is changed, it can introduce features that break the protocol, like choosing to not return a bool on transfer(), or changing the balance over time like a rebasing token.

Impact

Protocol may break in future for using that specific token.

Tools Used

Manual Analysis

Recommendations

Add a function to add/remove tokens from the whitelist.