How much was lost in the Yearn Ether hack?

The Yearn Ether hack resulted in $9.0M in losses on November 30, 2025.

What attack technique was used in the Yearn Ether exploit?

The Yearn Ether exploit utilized yETH stablepool Exploit. Understanding this attack vector is critical for smart contract auditors and developers building secure DeFi protocols.

How can developers prevent similar smart contract attacks?

Preventing smart contract hacks requires a combination of secure coding practices, thorough security audits, and understanding common attack vectors like reentrancy, oracle manipulation, and access control flaws. Smart Contract Hacking (SCH) provides hands-on training to help developers and auditors identify and prevent vulnerabilities before deployment.

Yearn Ether Hack

TOTAL LOST $9.0M

Medium Nov 30, 2025 yETH stablepool Exploit ethereum

Affected Chain ethereum Incident surface

Recovered - No recovery reported

All-Time Rank #323 By amount stolen

Auditors 4 Prior security audits

Incident Overview

yETH is a user-governed liquidity pool token consisting of various Ethereum Liquid Staking Derivatives (LSTs). The yETH pool is an Automated Market Maker (AMM) for LSTs. Each LST in the yETH pool is priced according to the amount of beacon chain ETH it represents.

Incident Report

Protocol / Project Yearn Ether

Date of Incident November 30, 2025

Affected Chain(s) ethereum

Attack Technique yETH stablepool Exploit

Classification Protocol Logic

Primary Source View Post-Mortem

Protocol Information

Protocol Type Indexes

Smart Contract Language Solidity

Official Website yeth.yearn.fi

Protocol Twitter/X @yearnfi

Market Context at Time of Hack

Token Price at Hack $3,258.91

Token Categories

Liquid Staking Tokens Ethereum Ecosystem

Protocol Links

GitHub Discord

What the Attacker Needed to Succeed

Understanding the prerequisites for this type of attack helps auditors identify protocols that are most at risk and helps developers build better defenses.

Technical Knowledge Deep understanding of yeth stablepool exploit and Solidity and EVM internals

Capital Required Seed capital to cover gas and initial position setup

On-Chain Access Ability to interact with ethereum smart contracts and deploy a custom exploit contract

Protocol Analysis Identification of the exploitable vulnerability in Yearn Ether's contract logic - root cause: protocol logic

Execution Speed Precise transaction ordering and timing to exploit the vulnerability within a single atomic block

Obfuscation Plan A strategy to launder and move stolen funds - typically through mixers, cross-chain bridges, or decentralized DEX swaps to resist tracing

What Auditors Should Check

Could this have been caught in audit? Likely — with a thorough yETH stablepool Exploit audit checklist and test coverage

Audited by Audit Report 1, Audit Report 2, Audit Report 3, Audit Report 4 — still lost $9.0M. Prior audits don't guarantee safety, especially after post-audit code changes.

If you're auditing a protocol with similar architecture to Yearn Ether, these are the critical security checks that could have prevented this incident (November 2025).

Verify all logic paths related to yETH stablepool Exploit are guarded by proper access controls and input validation
Review privileged functions (owner, admin, governance) for potential abuse vectors - centralization risks should be documented and bounded with timelocks or multi-sigs

Master these auditing techniques with hands-on labs and real exploit scenarios in the Smart Contract Hacking course.

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Security Audit History

Audit Report 1 Report
Audit Report 2 Report
Audit Report 3 Report
Audit Report 4 Report

Sources & References

01
Source 1 https://x.com/Togbe0x/status/1995240261816070482

Threat Assessment

Severity Level

MEDIUM

Attack Vector yETH stablepool Exploit
Root Cause Protocol Logic
Year 2025

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