# Mento audit contest Sherlock · Stablecoin · 24th October 2024 · #1 A public audit contest on Sherlock (stablecoin), completed on 24th October 2024. 0xSimao placed #1. 5 of his findings are published: 5 medium. ## What Mento is Mento issues local-currency stablecoins on Celo, cUSD and kin, exchanging them against a reserve through virtual AMM pools with oracle-guarded pricing, flow limits and a UBI-adjacent minting path. ## Scope The Sherlock competition covered the broker and reserve machinery: mint pricing and rounding, supply-contribution accounting on sells, trading limits as flows change direction, and the ratio scalars normalising decimals. ## Medium severity findings - [User to sell the last supply will make the exchange contribution forever stuck](https://0xsimao.com/findings/mento-sell-supply-contribution-stuck) - [`GoodDollarExchangeProvider::mintFromExpansion()` will change the price due to a rounding error in the new ratio](https://0xsimao.com/findings/mento-provider-mint-price-rounding) - [Malicious user may frontrun `GoodDollarExpansionController::mintUBIFromReserveBalance()` to make protocol funds stuck](https://0xsimao.com/findings/mento-frontrun-mint-ubi-stuck) - [`TradingLimits::update()` incorrectly only rounds up when `deltaFlowUnits` becomes 0, which will silently increase trading limits](https://0xsimao.com/findings/mento-limits-delta-flow-becomes) - [_getReserveRatioScalar() will give a lesser value than expected](https://0xsimao.com/findings/mento-ratio-scalar-lesser-expected) ## The contest [View the contest page](https://audits.sherlock.xyz/contests/598)