Oracle staleness risk: deprecated latestAnswer() used without freshness check

[shunfeng8421]

Summary

The assetPrice() function in contracts/Auditor.sol:356 uses Chainlink's deprecated latestAnswer() instead of latestRoundData(), with no staleness check on the returned price.

Vulnerability Details

// contracts/Auditor.sol:353-358
function assetPrice(IPriceFeed priceFeed) public view returns (uint256) {
    if (address(priceFeed) == BASE_FEED) return basePrice;
    int256 price = priceFeed.latestAnswer();  // <-- DEPRECATED, no staleness check
    if (price <= 0) revert InvalidPrice();
    return uint256(price) * baseFactor;
}

The IPriceFeed interface only exposes latestAnswer():

// contracts/utils/IPriceFeed.sol:7
function latestAnswer() external view returns (int256);

Risk

• latestAnswer() is explicitly deprecated by Chainlink
• No check on updatedAt timestamp — contract will use stale prices indefinitely if oracle stops updating
• Affects ALL liquidation calculations (liquidate(), accountLiquidity()) through assetPrice()
• During network congestion or oracle downtime, stale prices could lead to unfair liquidations

Recommended Fix

Update IPriceFeed to include latestRoundData() and add staleness validation:

function assetPrice(IPriceFeed priceFeed) public view returns (uint256) {
    if (address(priceFeed) == BASE_FEED) return basePrice;
    (, int256 price, , uint256 updatedAt, ) = priceFeed.latestRoundData();
    require(price > 0, "Invalid price");
    require(block.timestamp - updatedAt < STALENESS_THRESHOLD, "Stale price");
    return uint256(price) * baseFactor;
}

References

• Chainlink docs: https://docs.chain.link/data-feeds/api-reference#latestanswer
• Similar issues: Cream Finance exploited via oracle price manipulation

[coderabbitai]

⚠️ Possible Duplicate Issue(s)

• Lack of Oracle staleness check can cause over-borrowing and unfair liquidations #794

---

📝 Issue Planner

_{Check the box below or use the @coderabbitai plan command to generate an implementation plan and prompts that you can use with your favorite coding assistant.}

• Create Plan

---

🧪 Issue enrichment is currently in open beta.

You can configure auto-planning by selecting labels in the issue_enrichment configuration.

To disable automatic issue enrichment, add the following to your .coderabbit.yaml:

issue_enrichment:
  auto_enrich:
    enabled: false

💬 Have feedback or questions? Drop into our discord!