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code-423n4 / 2021-07-wildcredit-findings

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Use of deprecated Chainlink function `latestAnswer` #143

Closed code423n4 closed 3 years ago

code423n4 commented 3 years ago

Handle

shw

Vulnerability details

Impact

According to Chainlink's documentation, the latestAnswer function is deprecated. This function does not error if no answer has been reached but returns 0, causing an incorrect price fed to the UniswapV3Oracle.

Proof of Concept

Referenced code: UniswapV3Oracle.sol#L94

Referenced documentation: Chainlink - Deprecated API Reference Chainlink - Migration Instructions Chainlink - API Reference

Recommended Mitigation Steps

Use the latestRoundData function to get the price instead. Add checks on the return data with proper revert messages if the price is stale or the round is uncomplete, for example:

(uint80 roundID, int256 price, , uint256 timeStamp, uint80 answeredInRound) = wethOracle.latestRoundData();
require(answeredInRound >= roundID, "...");
require(timeStamp != 0, "...");
talegift commented 3 years ago

75