Pyth EVM

Pyth Network is a pull-based oracle that delivers high-frequency price data to EVM chains. Unlike push oracles (Chainlink) where oracle nodes update on-chain prices on a schedule, Pyth publishes prices off-chain via Hermes and consumers submit price updates on-chain when they need fresh data. This enables sub-second update latency, lower oracle costs, and prices across 500+ feeds on 70+ chains.

What You Probably Got Wrong

• Price updates can be front-run -- ALWAYS combine updatePriceFeeds + price consumption in a SINGLE transaction. If you expose updatePriceFeeds as a standalone public function, an attacker can sandwich your price update: observe the pending update, trade before it lands, then trade after. The ONLY safe pattern is a single function that accepts bytes[] calldata pythUpdateData, calls updatePriceFeeds, and immediately reads the price. Never separate update from read.

• Confidence interval matters -- wide confidence = unreliable price. Every Pyth price includes a confidence interval (1 standard deviation). A BTC price of $67,890 with confidence $680 means the true price is between $67,210 and $68,570 with ~68% probability. Reject prices where conf > price * 0.01 (1%) for lending protocols, or your protocol becomes exploitable during high-volatility events.

• Update fee is dynamic -- do NOT hardcode msg.value. The fee depends on the number of price updates in the updateData. Always call pyth.getUpdateFee(updateData) first and pass the exact amount as msg.value. Hardcoding 1 wei will revert when the fee changes.

• getPriceUnsafe() returns arbitrarily stale data. It is only safe to call immediately after updatePriceFeeds in the same transaction. In any other context, use getPriceNoOlderThan(priceFeedId, maxAge) which reverts if the price is too old.

• Pyth uses a PULL model -- prices are NOT already on-chain. You must fetch price update data from Hermes (off-chain) and submit it on-chain. This is the opposite of Chainlink where oracles push updates on a heartbeat schedule. If your contract tries to read a Pyth price without first calling updatePriceFeeds, you get stale or nonexistent data.

• Price feed IDs are bytes32, NOT contract addresses. Each feed has a unique bytes32 identifier that is the SAME across all chains. Feed 0xff61491a... is always ETH/USD whether you are on Ethereum, Arbitrum, or Base. The Pyth contract address varies by chain, but feed IDs do not.

• Pyth contract addresses VARY by chain. Ethereum and Avalanche use 0x4305FB66699C3B2702D4d05CF36551390A4c69C6. Arbitrum, Optimism, and Polygon use 0xff1a0f4744e8582DF1aE09D5611b887B6a12925C. BNB Chain uses 0x4D7E825f80bDf85e913E0DD2A2D54927e9dE1594. Always look up the correct address for your target chain.