Moonwell Lending Hack
Reported loss
$8.7M
Collateral Accounting and Oracle Price Manipulation
What happened
On 27 August 2026, an actor manipulated Moonwell’s MAMO market on Base by combining collateral accounting inflation with a manipulated MAMO oracle price. Moonwell’s post-mortem distinguishes initial capital, gross borrowing, proceeds, and remaining debt rather than treating them as one loss figure.
Technical root cause
Direct underlying transfers could increase mMAMO’s exchange rate outside the mint-path supply cap, while the market accepted a rapidly elevated MAMO price for collateral valuation.
How it happened
- The principal account supplied MAMO, then transferred additional MAMO directly to the mMAMO contract without minting receipt tokens.
- That raised the exchange rate for existing mMAMO shares.
- Purchases in thin liquidity raised the MAMO/USD price used by the market, enabling additional borrowing before liquidations began.
Protocol details
Classification
Oracle Manipulation / Borrowing and Lending
Protocol Type
Lending
Implementation language
Solidity
Protocol links
Website
@MoonwellDeFi
Security review history
- Halborn View report
Evidence
Understand the attack patterns
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