Balancer V2 (+ Beethoven X fork): Linear pool rounding-down logic → cached rate manipulation → boosted pool drain
Balancer lost $2.1M when a known rounding bug in Linear Pool math — publicly disclosed 5 days earlier — was exploited in pools that were never included in any audit scope.
Summary #
Balancer V2 (+ Beethoven X fork) suffered a DEX / AMM (Weighted Pools, Boosted Pools) on 2023-08-27, resulting in a loss of approximately $2M.
What happened #
Balancer lost $2.1M when a known rounding bug in Linear Pool math — publicly disclosed 5 days earlier — was exploited in pools that were never included in any audit scope.
Linked factors #
- RD-F-001 — related : ★ Audit scope mismatch — alternate field name [via dashboard_risk_factors/Exploited code in scope?: No — Boosted Pools and Linear Pools explicitly out of scope for all linked audit reports] || ★ Direct: Audit scope mismatch (report commit ≠ deployed bytecode) [via cross-hack: Factor 1: Audit Scope Mismatch]
- RD-F-004 — related : Audit count likely 0; floor display [via dashboard_risk_factors/Vulnerability in audited or unaudited code: Unaudited code (Boosted Pools explicitly out of scope)]
- RD-F-008 — illustrative : Ignored bug bounty disclosure — adjacent [via cross-hack: Factor 3: Ignored / Dismissed Security Disclosure]
- RD-F-077 — related : Auto-linked by C.4 triage 2026-05-07
- RD-F-098 — illustrative : TVL anomaly — % drop in <1h vs 30d baseline [via realtime_signals/TVL exit early (Y/N): Y — majority of at-risk TVL was withdrawn in the 5-day window; only remaining stragglers were drained]
- RD-F-126 — related : Is-a-fork-of (Cat 8 anchor) [via dashboard_risk_factors/Forked?: No — original Balancer; Beethoven X is a Balancer fork that was also hit]
- RD-F-177 — related : Cat 13: Prior known-ignored disclosure [via cross-hack: Factor 3: Ignored / Dismissed Security Disclosure]