Yearn yETH Pool (2025) — Crypto Hack
Partially RecoveredAn attacker minted 235 septillion yETH while depositing only 16 wei by exploiting unsafe math and stale cached values in Yearn's yETH pool, draining ~$9M.
Summary
An attacker minted 235 septillion yETH while depositing only 16 wei by exploiting unsafe math and stale cached values in Yearn's yETH pool, draining ~$9M.
How It Was Compromised — Overflow/Rounding Vulnerability via unsafe_mul overflow and unsafe_sub underflow with stale cached packed_vbs[] values in _calc_supply
On November 30-December 1, 2025, the Yearn yETH pool was exploited through unsafe math operations (unsafe_mul overflow, unsafe_sub underflow) combined with stale cached packed_vbs[] values in the _calc_supply function. The attacker minted 235 septillion yETH (a 41-digit number) while depositing only 16 wei, draining approximately $9M. Approximately $2.4M was recovered by burning pxETH held by the attacker.
Fund Flow & Laundering Analysis
No laundering activity observed. ~$2.4M recovered by burning pxETH held by the attacker; remaining funds unrecovered.