An attacker turned 250 dollars of SAUCE tokens into a nine million dollar loan because an oracle verifier accepted a blank signature. That is the whole story, and it is bad enough.
At 00:51 UTC on July 11, someone deposited 250 SAUCE tokens, worth only a few dollars, into Bonzo Lend, the largest lending protocol on the Hedera network. Then they submitted a price update to Supra's on-demand oracle contract claiming SAUCE was suddenly worth roughly a trillion times more than it actually was. The update carried a zeroed signature instead of a real one from Supra's authorized committee. Supra's verifier waved it through anyway. Eight seconds later, the attacker walked out with 6.63 million USDC and 34.5 million wrapped HBAR, according to a report from CoinDesk.
You don't need a security background to see the problem. A signature check exists to confirm that whoever sent a message actually had the authority to send it. Supra's contract treated a blank field as a pass. Bonzo's own team later wrote that its lending contracts did what they were built to do. They read the oracle's on-chain price and calculated borrowing limits from it. The bug wasn't in the loan logic. It was one layer up, in a piece of infrastructure Bonzo didn't build and couldn't audit itself.
The fallout was immediate. Hedera's total value locked across DeFi fell nearly 40% within 24 hours, based on data reported by CryptoRank.io and Cointelegraph. Bonzo's own TVL collapsed 77%. Bonzo has since paused its lending and points programs while it investigates, though its vaults, bridge, and staking products kept running. The attacker moved fast on the exit too, bridging more than $5.25 million from Hedera over to Ethereum, according to CryptoTimes.
A White Hat Complicates the Count
There's a stranger footnote. A second wallet, which Bonzo refers to as Wallet B, spotted the same window of inflated pricing and borrowed close to a million dollars using the identical exploit. Then it reached out to Bonzo through Discord, identified itself as a white hat, and said it intends to return the funds. Maybe it will. Bonzo has excluded that million from its headline loss figure while the two sides work out the recovery. Nobody outside that Discord channel can say whether the promise holds once the dust settles.
The Same Bug, Twice in Two Weeks
This is the second time in under two weeks that a third-party price system, not the lending logic itself, has been the actual point of failure on a DeFi protocol. Ten days apart. On July 1, Edel Finance halted its lending protocol after an attacker exploited how its tokenized Google stock wrapper converted between GOOGLx and wGOOGLx. The move inflated the wrapped token's value by about 78 times and created roughly $403,000 in bad debt, according to CoinDesk. Chainlink's underlying price feed was accurate the whole time. The exploit lived in the conversion mechanism sitting next to it.
Different bug, same shape. Protocols keep building collateral ratios, liquidation thresholds, and interest curves on top of a price feed they trust by default. When that feed is wrong, none of the careful math underneath matters. Supra has acknowledged the vulnerability and pushed a fix to the affected verifier contract on Hedera mainnet. Hedera's own account on X confirmed the patch and said security researchers were still combing through the rest of the system.
Frankly, a zeroed signature passing verification isn't an exotic attack. It's the kind of check a competent audit should catch on day one. Bonzo built its risk model assuming Supra's oracle had already solved that problem. It hadn't. Every protocol that plugs into a third-party price feed is making the same bet right now. Most of them have no way of knowing whether their oracle's verifier has the same hole until someone finds it the hard way.
Bonzo says it will share more on reimbursements and remediation once its investigation wraps. That's the easy part to promise. For now, Hedera's DeFi ecosystem is left explaining to depositors why a token worth a few dollars was briefly treated as collateral worth tens of millions.
Also read: The Name Was Crypto • What Is a Perp DEX and Why Traders Are Leaving Centralized Exchanges • Two npm attacks in four days show crypto's weak point is the supply chain
