How much was lost in the GMX V1 Perps hack?

The GMX V1 Perps hack resulted in $42.0M in losses on July 09, 2025.

What attack technique was used in the GMX V1 Perps exploit?

The GMX V1 Perps exploit utilized Re-entrancy 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.

GMX V1 Perps Hack

TOTAL LOST $42.0M

High #142 All-Time Jul 09, 2025 Re-entrancy Exploit arbitrum

Affected Chain arbitrum Incident surface

Recovered - No recovery reported

All-Time Rank #142 By amount stolen

Auditors 1 Prior security audit

Incident Overview

GMX is a decentralized spot and perpetual exchange that supports low swap fees and zero price impact trades. Trading is supported by a unique multi-asset pool that earns liquidity providers fees from market making, swap fees, leverage trading (spreads, funding fees & liquidations) and asset rebalancing.

This is classified as a Reentrancy . Compare similar hacks →

Incident Report

Protocol / Project GMX V1 Perps

Date of Incident July 09, 2025

Affected Chain(s) arbitrum

Attack Technique Re-entrancy Exploit

Classification Protocol Logic

Primary Source View Post-Mortem

Protocol Information

Protocol Type Derivatives

Smart Contract Language Solidity

Official Website gmx.io/

Protocol Twitter/X @GMX_IO

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 re-entrancy exploit and Solidity and EVM internals

Capital Required Seed capital to cover gas and initial position setup

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

Protocol Analysis Identification of the exploitable vulnerability in GMX V1 Perps'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 Re-entrancy Exploit audit checklist and test coverage

Audited by Audit Report 1 — still lost $42.0M. Prior audits don't guarantee safety, especially after post-audit code changes.

If you're auditing a protocol with similar architecture to GMX V1 Perps, these are the critical security checks that could have prevented this incident (July 2025).

Verify all logic paths related to Re-entrancy Exploit are guarded by proper access controls and input validation - see the Reentrancy attack class for patterns
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

Related Attack Classes

The technique used in this hack maps to these vulnerability classes in our security curriculum:

See all Reentrancy examples →

Reentrancy

Sources & References

01
Source 1 https://x.com/peckshield/status/1942947860645134450

Threat Assessment

Severity Level

HIGH

Attack Vector Re-entrancy Exploit
Root Cause Protocol Logic
Year 2025

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