{"id":485,"date":"2026-02-03T14:54:02","date_gmt":"2026-02-03T14:54:02","guid":{"rendered":"https:\/\/web3fuel.io\/article\/?p=485"},"modified":"2026-02-09T18:27:06","modified_gmt":"2026-02-09T18:27:06","slug":"sonne-finance-hack","status":"publish","type":"post","link":"https:\/\/web3fuel.io\/article\/sonne-finance-hack\/","title":{"rendered":"Sonne Finance Hack: When Forking Code Costs $20 Million"},"content":{"rendered":"

Sonne Finance Hack: When Forking Code Costs $20 Million<\/b><\/h1>\n<\/div><\/div>

Everything about this exploit was avoidable. The vulnerability was known. The fix was simple. The warning signs were everywhere. Sonne Finance paid $20 million to learn a lesson that was already taught three times before.<\/span><\/em><\/p>\n<\/div><\/div><\/div><\/div>

by Alex G.<\/a><\/span> | Feb 3, 2026<\/span><\/p><\/div><\/div><\/div><\/div>

On May 14, 2024, users of Sonne Finance learned that trust isn't enough.<\/span><\/p>\n

In 25 minutes, an attacker drained $20 million from the protocol using a vulnerability that wasn't new, wasn't sophisticated, and wasn't even a secret. The same exploit had already hit three other protocols in the previous 12 months. Sonne Finance had been warned by their auditors. The fix was well-documented.<\/span><\/p>\n

And yet, it happened anyway.<\/span><\/p>\n

What makes this exploit particularly instructive isn't the technical complexity, it's the simplicity. This is a case study in what happens when teams fork code they don't fully understand, ignore audit warnings, and deploy critical infrastructure without proper operational security.<\/span><\/p>\n

Here's exactly how it went down, why it keeps happening, and what it means for the future of DeFi security.<\/span><\/p>\n<\/div><\/div>

\/\/ <\/span>TL;DR - The $20 Million Lesson<\/b><\/strong><\/h2>\n<\/div><\/div>

What happened:<\/b><\/p>\n

    \n
  • $20 million stolen<\/strong> from Sonne Finance on Optimism on May 14, 2024.<\/span><\/li>\n
  • Attack method:<\/strong> Precision loss \"donation attack\" exploiting empty Compound V2 market.<\/span><\/li>\n
  • Historical context:<\/b> Same vulnerability had already hit Hundred Finance ($7.4M), Onyx Protocol. ($2M), and Starlay Finance ($2.1M)<\/span><\/li>\n
  • Audit warning:<\/b> yAudit specifically flagged this exact vulnerability in their security report.<\/span><\/li>\n
  • Root cause:<\/b> Permissionless timelock execution on Optimism + empty market initialization + ignored audit findings.<\/span><\/li>\n
  • Laundering:<\/b> Funds immediately bridged to multiple chains via Stargate Finance.<\/span><\/li>\n<\/ul>\n

    Why it matters:<\/b><\/p>\n

    <\/b><\/p>\n

      \n
    • Over 100 active Compound V2 forks exist.<\/span><\/li>\n
    • Demonstrates risk when teams fork code without understanding it.<\/span><\/li>\n
    • Shows that audits are meaningless if teams don't actually fix the findings<\/span><\/li>\n
    • Proves that operational security (deployment procedures) is just as critical as code security.<\/span><\/li>\n<\/ul>\n<\/div><\/div><\/div><\/div>
      \n

      \n Table of Contents\n \u25bc<\/span>\n <\/h3>\n
        <\/ul>\n<\/div>\n\n