A NullMeridian record Andromeda Logs

NullMeridianLog

9 Jul 2025

GMX V1 Arbitrum: OrderBook Reentrancy Inflated GLP, ~$40M Moved

GMX: on 9 Jul 2025 a live V1 vulnerability on Arbitrum let ~$40M of GLP liquidity be withdrawn. Funds returned after outreach; $5M bounty paid. V2 unaffected.

  • Event date
  • Incident typeSmart-contract exploit
  • Bug classReentrancy
  • Published

Loss, as sourced

About $40 million of GLP liquidity compromised and withdrawn, then fully returned following outreach, per GMX. A $5m bug bounty was paid.

Traceability

Primary sources

  1. 01gmxio.substack.comGMX: GLP funds on Arbitrum fully recovered, 16 Jul 2025 (opens in a new tab)

In brief

Root cause: Per GMX: reentrancy via OrderBook into Vault.increasePosition, bypassing average-short-price accounting, manipulating BTC average short price and inflating GLP before redeem.

Timeline, as sourced: Per GMX: 9 Jul disclosure/exploit; funds returned; V1 mint/redeem disabled on Arbitrum; V2 normal.

Account, as sourced

Claimed (GMX) (update (opens in a new tab)): ~$40M returned; $5M bounty paid to 0xDF3340A436c27655bA62F8281565C9925C3a5221.

Summaries of public sources as of the published date; except where marked (on-chain), not independently verified by NullMeridian. Figures are the sources’ own and are attributed; where sources disagree, each is given. Sources may since have changed. Not legal, financial or investment advice.

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