DeFi Has Seen Resolv’s $25M USR Exploit Many Times Before

On a quiet Sunday morning, someone turned $100,000 into $25 million in about seventeen minutes.

The target was Resolv, a yield-bearing stablecoin protocol. By the time Resolv paused its contracts, its dollar-pegged stablecoin USR had crashed to pennies. It remains deeply depegged, trading around $0.25 as of this writing, down more than 70% on the week.

The blast radius extended well beyond Resolv. Fluid/Instadapp absorbed more than $10 million in bad debt and had outflows of over $300 million in a single day, the worst outflow in its history. Fifteen Morpho vaults were hit. Euler, Venus, Lista DAO, and Inverse Finance all moved to pause USR-related markets.

The mechanism that caused the initial hack to spread its damage – pricing a depegged stablecoin at $1 in a lending market– is not new. It happened at least four times in the past fourteen months.

How the Hack Worked

USR’s minting followed a two-step off-chain process: a user deposited USDC via the `requestSwap’ function, and a privileged off-chain signing key, the `SERVICE_ROLE’, finalized the amount of USR to issue via `completeSwap’. The contract enforced a minimum output but had no maximum. Whatever the key holder signed, the contract honored.

The attacker gained access to that key through Resolv’s AWS Key Management Service. They submitted two USDC deposits, totaling roughly $100,000–$200,000, and used the compromised key to authorize 80 million USR in return. Etherscan shows two transactions worth 50 million USR and 30 million USR, minted in minutes.

“The Resolv USR exploit wasn’t a bug — it was a feature working exactly as designed. And that’s the problem,” said on-chain analyst Vadim (@zacodil).

The SERVICE_ROLE was a regular externally owned address, not a multisig. The admin key had multisig protection, but the mint key didn’t.

“Resolv was audited 18 times,” Vadim said. “One finding was literally called ‘Missing upper [limit]'”

The attacker exited methodically, converting minted USR into wstUSR (the staked wrapped version) to slow the market impact, then rotating through Curve, Uniswap, and KyberSwap into ETH. The attacker’s wallet holds approximately 11,400 ETH (~$24M). Resolv’s collateral pool, the ETH and BTC backing the system, survived intact even as the stablecoin crashed.

How the Contagion Spread

The Resolv hack is two incidents stacked on top of each other. The first is the mint exploit. The second is a cascading lending market failure.

When USR and wstUSR collapsed, every lending market that had accepted them as collateral faced the same problem: their oracle was still pricing wstUSR near $1.

Omer Goldberg, founder of risk analytics firm Chaos Labs, documented the mechanism. His key finding was that “The oracle is hardcoded and thus never repriced. wstUSR was marked at $1.13 while trading at ~$0.63 on secondary markets.”

Traders bought cheap wstUSR on the open market and posted it as collateral at the oracle’s $1.13 valuation on Morpho or Fluid, then borrowed USDC against it and walked away.

At Fluid, the team secured short-term loans to cover 100% of the bad debt and committed to making every user whole. At Morpho, co-founder Paul Frambot said ~15 vaults had significant exposure, all in high-risk, long-tail collateral strategies.

Prominent curator Gauntlet said that “A few high-yield vaults had limited exposure.”

But D2 Finance challenged that framing directly, posting onchain data showing Gauntlet’s flagship “USDC Core vault” had $4.95M allocated to the wstUSR/USDC market. Goldberg later said Gauntlet vaults accounted for 98% of lender liquidity in that market.

“I think the curator industry is poorly designed because there’s not actual curation happening,” said Marc Zeller on X.

Resolv, Gauntlet, Morpho and Fluid did not respond to The Defiant’s requests for comments by press time.

A Recurring Failure

This is not a novel attack. In January 2025, Usual Protocol’s USD0++ was hardcoded at $1 on Morpho vaults by curator MEV Capital. Usual abruptly changed its redemption floor to $0.87 without warning, leaving lenders stuck in the MEV Caital vault as utilization spiked to 100%.

In November 2025, Stream Finance’s xUSD collapsed after curators had routed USDC deposits into leverage loops backed by the synthetic stablecoin, leaving an estimated $285M–$700M at risk across Morpho, Euler, and Silo when its oracle refused to update. Moonwell suffered back-to-back oracle failures in October and November 2025, generating more than $5 million in combined bad debt.

What It Means for the Curator Model

Morpho’s architecture outsources all risk decisions to third-party “curators” who build vaults, choose collateral, set loan-to-value ratios, and select oracles. The theory is that specialist firms have deeper expertise, competition drives better risk management, and the protocol enforces rules.

But curators earn fees on yield generated, which creates an incentive to accept riskier, higher-yield collateral, like yield-bearing stablecoins. The downside is that when those stablecoins depeg, the losses fall on depositors, not on the curator. In the Resolv case, some curators had automated bots still refilling affected vaults hours after the exploit started, deepening losses.

The reason to hardcode oracles for yield-bearing stablecoins is to prevent short-term volatility from triggering unnecessary liquidations. But that protection only works as long as the stablecoin remains stable.

Chainalysis said in a post-mortem that real-time chain detection is needed.

“The on-chain smart contract worked perfectly. The broader system design and off-chain infrastructure apparently did not,” the analytics firm said.