Single Oracle Source, No Fallback

SAFE-0204 Oracle / Price Checked automatically by the scanner

What goes wrong

Pricing depends on a single oracle with no secondary source or deviation cross-check. If that feed is deprecated, paused, or compromised, the protocol has no safe fallback and either bricks or prices on a bad number.

The vulnerable pattern

proof of concept — how it is exploited

// Chainlink deprecates the feed; latestRoundData reverts.
// with no fallback, every deposit/withdraw/liquidation reverts
// -> protocol frozen until an upgrade.

How to fix it

the pattern that is safe

uint256 p1 = chainlink.price();
uint256 p2 = fallbackOracle.price();
require(_within(p1, p2, MAX_DEVIATION), "oracle disagreement");

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Use a primary + fallback oracle with a deviation check.

Where this has happened

Largest recorded losses in the same failure class — related, not the same bug:

$130M · 2021 Cream Finance Oracle manipulation · 2021 $115M · 2022 Mango Markets Oracle manipulation · 2022

Related vulnerabilities in Oracle / Price

SAFE-0022Spot-Price Oracle Manipulation critical · Oracle / Price SAFE-0023Flash-Loan Price Manipulation critical · Oracle / Price SAFE-0024Stale / Unchecked Oracle Data high · Oracle / Price SAFE-0101Spot-Price Oracle from AMM Reserves high · Oracle / Price SAFE-0102Chainlink Feed Without Staleness / Round Check high · Oracle / Price SAFE-0201TWAP Window Too Short to Resist Manipulation high · Oracle / Price SAFE-0025Insufficient TWAP Window / Manipulable TWAP medium · Oracle / Price SAFE-0103Price Feed Missing Sanity Bounds medium · Oracle / Price

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