Hack history / 2025 / Hack or exploit
Balancer V2
Hack or exploit on Nov 3, 2025 · Rounding Error
SOURCES AGREE ON DATE AND LOSS · 5 SOURCES
Lost
$120.5M
sources: $110M to $128M
Returned
none listed
as the sources state it
Rank
#47
among thefts by dollars lost
What happened
On November 3, 2025, Balancer V2's Composable Stable Pools were exploited for $128M via a rounding-down flaw in batchSwap invariant calculation. Minuscule discrepancies in each transaction compounded across rapid successive swaps, gradually deflating pool reserves across chains.
Details
- Date
- Nov 3, 2025
- Kind
- Hack or exploit
- Method
- Rounding Error
- How in
- Smart contract bug
- Target
- DeFi protocol
- Chains
- Ethereum, Arbitrum, Base, Polygon, Sonic, Optimism
After the theft
- Recovered or seized
- yes, amount not stated
“As of November 19, coordinated mitigation efforts enabled several security measures to be deployed promptly after the issue was discovered, resulting in approximately $45.7 million in user funds being protected or recovered.” (SlowMist Hacked)
Related incidents
Balancer V1 2026 · Hack or exploit · $250K
Balancer V1 2026 · Hack or exploit · $234K
Balancer V2 2023 · Hack or exploit · $238K
Balancer V2 2023 · Hack or exploit · $2M
Balancer 2023 · Hack or exploit · $11.9M
Balancer V1 2026 · Hack or exploit · $234K
Balancer V2 2023 · Hack or exploit · $238K
Balancer V2 2023 · Hack or exploit · $2M
Balancer 2023 · Hack or exploit · $11.9M
Cite this page
SwanBluechip, "Balancer V2 hack, Nov 3, 2025: $120.5M lost", Crypto hack history, https://swan-hack-tracker.pages.dev/history/i/ht5b2e086d42/ (data as of 2026-10-31).