# 1inch Fee Extension audit Sherlock · DEX aggregator · 14th April 2025 A private security review of 1inch (DEX aggregator), conducted with Sherlock and completed on 14th April 2025 over 4 days. 0xSimao disclosed 3 findings: 3 low. ## What 1inch is 1inch's limit order protocol lets makers sign orders off-chain that takers fill on-chain, and the Fusion layer runs resolver auctions over those orders. The fee extension is the contract that computes and collects protocol and integrator fees, with whitelist discounts, at fill time. ## Scope The Sherlock review covered the fee extension contract: the taker-fee calculation and its rounding across order sizes and token decimals, the uni-transfer gas path, and the whitelist discount maths. ## Low severity findings - [Taker fee is underestimated due to incorrect fee calculation](https://0xsimao.com/findings/1inch-taker-fee-underestimated-calculation) - [`uniTransfer()` limits the gas limit to 5k in outdated 1inch solidity-utils lib](https://0xsimao.com/findings/1inch-uni-transfer-gas-1inch) - [Significant rounding error in whitelist discount that could be avoided](https://0xsimao.com/findings/1inch-rounding-whitelist-discount-avoided) ## The report [Download the report (PDF)](https://0xsimao.com/reports/2025-04-14-1inch.pdf)