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code-423n4 / 2023-01-numoen-findings

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Wrong init code hash #206

Open code423n4 opened 1 year ago

code423n4 commented 1 year ago

Lines of code

https://github.com/code-423n4/2023-01-numoen/blob/2ad9a73d793ea23a25a381faadc86ae0c8cb5913/src/periphery/UniswapV2/libraries/UniswapV2Library.sol#L27

Vulnerability details

Impact

An init code hash is used to calculate the address of UniswapV2 pair contract. But the init code hash is not same as the latest UniswapV2 repository.

Proof of Concept

UniswapV2Library.pairFor uses the following value as the init code hash of UniswapV2Pair. 

    hex"e18a34eb0e04b04f7a0ac29a6e80748dca96319b42c54d679cb821dca90c6303" // init code hash

But it is different from the init code hash of the uniswap v2 repository.

I tested this using one of the top UniswapV2 pairs. DAI-USDC is in the third place here.

The token addresses are as follows:

DAI: 0x6B175474E89094C44Da98b954EedeAC495271d0F

USDC: 0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48

And the current UniswapV2Factory address is 0x5C69bEe701ef814a2B6a3EDD4B1652CB9cc5aA6f here.

The pair address calculated is 0x6983E2Da04353C31c7C42B0EA900a40B1D5bf845. And we can't find pair contract in the address.

So I think the old version of UniswapV2Factory and pair are used here. And it can cause a risk when liquidity is not enough for the pair.

Tools Used

Manual Review

Recommended Mitigation Steps

Integrate the latest version of UniswapV2.

c4-judge commented 1 year ago

berndartmueller marked the issue as primary issue

c4-sponsor commented 1 year ago

kyscott18 marked the issue as sponsor acknowledged

kyscott18 commented 1 year ago

I should have been more specific, but the init code hash that I submitted is the sushiswap one.

c4-judge commented 1 year ago

berndartmueller marked the issue as satisfactory

c4-judge commented 1 year ago

berndartmueller marked the issue as selected for report