GoPlus Warns of Critical Vulnerability in Balancer Forks Following Multiple DeFi Exploits

Executive Summary

Blockchain security firm GoPlus has alerted the decentralized finance (DeFi) community to a critical vulnerability impacting all protocols forked from Balancer, leading to multiple exploits and significant financial losses across several blockchain networks.

The Event in Detail

GoPlus formally announced a widespread vulnerability affecting all DeFi protocols built on the Balancer codebase. This alert followed observations of multiple successful exploits targeting these platforms. One notable incident involved the 402bridge cross-chain protocol, where its contract creator transferred ownership to an attacker's address (0x2b8F). This attacker subsequently invoked the transferUserToken function to drain USDC from over 200 authorized wallets, resulting in losses totaling 17,693 USDC. The attacker then converted these funds to ETH and bridged them to Arbitrum via multiple cross-chain transactions. GoPlus has advised users who interacted with the 402bridge project to immediately revoke token approvals for the affected contract.

Separately, blockchain security firm BlockSec identified and mitigated a series of sophisticated attacks targeting Balancer and its forked protocols across six blockchain networks. These attacks resulted in substantial financial losses, with Ethereum alone experiencing an estimated $70 million in damages. BlockSec’s intervention reportedly prevented an additional $83.7 million in potential losses across Ethereum, Base, Polygon, Sonic, Arbitrum, and Optimism chains. These events prompted immediate security responses, including protocol pauses and urgent user notifications to withdraw funds from impacted platforms.

Financial Mechanics and Exploit Vectors

The exploits targeting Balancer forks underscore critical vulnerabilities often found in smart contract logic and permissioning. In the case of 402bridge, the mechanism involved the malicious transfer of contract ownership, allowing the new owner to execute functions like transferUserToken and drain assets from users who had granted excessive token approvals. This highlights a common attack vector where broad token approvals, often required for minting or other DeFi interactions, can be abused if a protocol's underlying security is compromised.

Broader analyses by security firms point to pervasive issues. SlowMist, another blockchain security firm, reported that Web3 security breaches led to $266 million in losses in May 2025 alone. A significant incident during this period was the Cetus Protocol exploit on May 22, which severely disrupted liquidity pools and token pairs, particularly within the Sui ecosystem. SlowMist's investigations consistently identify smart contract vulnerabilities and insufficient auditing as primary contributors to these extensive exploits.

Market Implications and Response

The series of attacks on Balancer forks and other DeFi protocols has significantly impacted market confidence, particularly within the decentralized finance sector. Such breaches typically lead to reduced trading volumes and increased price slippage as market participants adopt more cautious stances. The Balancer (BAL) token itself reflects this sentiment; as of November 3, 2025, BAL traded at $0.95, with a market capitalization of $64,489,536.00 and a 24-hour trading volume of $3,384,632.53. Recent data from CoinMarketCap indicated a 3.80% drop in BAL's value over 24 hours, with further declines observed over a 90-day period.

In response to these ongoing security threats, developers across the Web3 ecosystem are accelerating patch deployments and initiating more thorough audits. The emphasis on strengthening security measures, revoking unnecessary token approvals, and improving smart contract resilience is critical to restoring trust and stabilizing these increasingly interconnected financial ecosystems.