ZachXBT Warns of New EVM Chains Security Risk: Cause Still Unknown
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Key Takeaways
A critical smart-contract flaw in Balancer V2 allowed unauthorized withdrawals totaling over $100 million.
The incident spanned multiple networks and assets, exposing systemic vulnerabilities in DeFi architecture.
Forked protocols sharing Balancer’s codebase face potential risks from the same exploit.
Continuous auditing, layered security, and prompt response mechanisms are vital to prevent similar breaches.
On Nov. 3, 2025, the decentralized finance (DeFi) platform Balancer suffered one of the largest crypto exploits of the year. Early blockchain data indicates losses ranging between $100 million and $128 million, impacting users across several networks.
Balancer Hack: Stolen assets across multiple chains exceed $116M | Source: @RoundtableSpace on X
Balancer’s team quickly confirmed that an exploit had occurred, launching an immediate investigation in collaboration with leading blockchain security firms. The attack targeted Balancer’s V2 smart-contract architecture, affecting liquidity pools on Ethereum mainnet and multiple layer-2 networks.
How Balancer’s V2 Vulnerability Led to a $128 Million DeFi Exploit
The incident has been traced back to a flaw in Balancer’s V2 contracts, specifically within internal functions responsible for handling user balances. While the team has yet to release a full post-mortem, blockchain analysts have provided insight into how the exploit was executed.
Vulnerable Functionality in Balancer V2
At the core of the issue was a vulnerability in the manageUserBalance and validateUserBalanceOp functions. These components handle internal transfers and withdrawals within Balancer’s vault system.
Due to a validation loophole, the attacker was able to initiate unauthorized withdrawal operations that bypassed access controls. This effectively gave them permission to drain assets from multiple user pools at once.
Impacted Pools and Networks
The exploit did not remain isolated to a single chain. Balancer operates across multiple networks, including Ethereum, Arbitrum, Optimism, Polygon, Base, and Sonic. Because Balancer V2 pools share a centralized vault architecture, a single vulnerability allowed the attacker to access funds stored on several blockchains. This design feature, intended for efficiency, unintentionally amplified the scale of the loss.
Balancer is a DeFi protocol built on the Ethereum blockchain. It operates as an automated market maker (AMM) and liquidity platform, allowing users to trade tokens, provide liquidity, and build custom financial products without relying on centralized intermediaries.
Core Concept
At its core, Balancer enables users to create and participate in liquidity pools, collections of tokens that facilitate automated trading based on mathematical formulas rather than traditional order books. Unlike most AMMs that restrict pools to two tokens in a 50/50 ratio, Balancer pools can hold up to eight different tokens with flexible weightings. This flexibility allows for more dynamic trading pairs and custom risk exposure.
Key Features
Multi-asset pools: Balancer supports multiple tokens per pool with customizable weightings (e.g., 80/20, 60/20/20).
Flexible fees: Pool creators can set transaction fees, allowing for optimization based on market conditions.
Non-custodial and permissionless: Users maintain control of their funds at all times, interacting directly with smart contracts.
Governance token (BAL): The BAL token gives holders voting rights in protocol decisions and incentivizes liquidity provision.
Vault architecture (V2): In its second version, Balancer introduced a single “Vault” smart contract that holds all user assets. This design improves efficiency by separating asset storage from the logic that manages pools and swaps.
Use Cases
Token swaps: Traders can exchange ERC-20 tokens directly through Balancer pools.
Liquidity provision: Users deposit assets into pools and earn a share of trading fees.
Portfolio management: Because of its flexible weightings, Balancer can function as a self-balancing portfolio, similar to an index fund that earns fees instead of paying them.
Market Fallout and On-Chain Impact of the Balancer Exploit
As the attack unfolded, real-time analytics platforms tracked millions of dollars’ worth of tokens flowing to new wallets controlled by the exploiter. The event triggered immediate reactions across the crypto community and financial markets.
Estimated Losses and Affected Assets
Initial assessments estimated around $70 million in losses, but as more transactions were uncovered, the figure rose beyond $128 million. The stolen funds consisted of large amounts of WETH, osETH, and wstETH, among other digital assets.
Analysts observed that the attacker used bridging and mixing protocols to obscure fund trails, complicating recovery efforts and on-chain monitoring.
Balancer exploit is a massive, forced liquidation event that could cause significant market volatility. | Source: @NekozTek on X
Market Impact on Balancer and DeFi
The news of the exploit caused the Balancer (BAL) token to drop sharply as traders reacted to the breach. Confidence in DeFi infrastructure was once again shaken, particularly for projects that share or fork Balancer’s codebase.
Many industry observers highlighted that this incident exposes a broader systemic risk, where one vulnerability in a widely adopted protocol can cascade across dozens of dependent ecosystems.
Affected Chains and Assets in the Balancer Exploit
The Balancer exploit had a widespread impact across multiple blockchains and digital assets, highlighting the interconnected nature of DeFi ecosystems. While Ethereum mainnet bore the brunt of the losses, several layer-2 and sidechain deployments were also compromised due to Balancer’s shared vault architecture.
Impacted Networks
The primary networks affected by the exploit included:
Ethereum Mainnet: The core of the breach, where the largest portion of assets was drained from Balancer V2 pools.
Arbitrum: The attacker conducted cross-chain operations through this layer-2, using it as a route to move stolen funds.
Optimism: Some Balancer liquidity pools on Optimism were exposed due to the shared contract logic.
Polygon: Smaller-scale losses were recorded, but the vulnerability still extended to this chain.
Base: Pools deployed on Base were also targeted, reflecting how Balancer’s vault system connected assets across networks.
Sonic: Exposure was recorded through Balancer’s cross-network integration, amplifying the attack’s scope.
This cross-chain exposure demonstrated the systemic risk of Balancer’s unified vault design, a structure meant to improve efficiency but which, in this case, magnified the exploit’s reach.
Affected Assets
The stolen funds primarily consisted of Ethereum-based and staked-Ethereum derivative tokens, including:
rsETH and rETH (Staked ETH Variants): Combined $8 million
Additional losses came from other token pools, pushing the total estimated damage between $100 million and $128 million across all chains and assets.
How the Balancer Exploit Exposed Systemic Risks Across the DeFi Ecosystem
Beyond the immediate financial damage, the Balancer hack raises deeper concerns about the safety and scalability of shared DeFi architectures. Multiple projects and networks are now conducting emergency audits to ensure they are not exposed to the same vulnerability.
Forked Projects and Systemic Risk
Balancer’s open-source code has been widely forked by DeFi protocols. Reports indicate that over two dozen Balancer-based projects could face similar security weaknesses. Some networks responded by temporarily halting transactions or even implementing emergency hard forks to contain the threat. This rapid response demonstrates the seriousness of the flaw and the interconnected nature of DeFi systems.
Risk to User Funds
For Balancer users, the exploit represents a direct threat to deposited assets. Funds in vulnerable pools were likely drained before the protocol could intervene.
This event serves as a reminder that even well-established DeFi platforms can carry inherent risks, especially when complex contract interactions are involved. Users are urged to practice caution, monitor their wallets, and follow official protocol updates closely.
As the chaos unfolded on-chain, X lit up with a mix of disbelief and morbid humor.
One user, @realtommybibi, flagged an unusual address that’s become somewhat of a DeFi folklore figure:
“There’s a wallet I noticed during this Balancer exploit that sends an on-chain message. $BAL
Looking at its history, I found that every time there’s a hack, this wallet sends a message congratulating the exploiter and asking them to buy him KFC 🍗.”
The KFC on-chain message linked to several hacks. | Source: @realtommybibi on X
According to Tommy B., the same wallet has appeared multiple times during major protocol breaches, including LiFi, UWU, Radiant, and WazirX, each time dropping a cheeky message to the hacker in the middle of multimillion-dollar exploits.
Balancer exploit. | Source: @realtommybibi on X
100M Balancer Exploit Tied to Tornado Cash Deposits
Moreover, blockchain data reveals that the attacker strategically funded their wallet through a series of small 0.1 Ether (ETH) deposits sent from the cryptocurrency mixer Tornado Cash, likely in an effort to evade detection. According to Conor Grogan, director at Coinbase, the exploiter had at least 100 ETH stored in Tornado Cash smart contracts, a sign that the funds may have originated from earlier hacks.
He noted on X that “Balancer was hacked for around $100 million. Hacker seems experienced:
Seeded account via 100 ETH and 0.1 Tornado Cash deposits. No opsec leaks.
Since there were no recent 100 ETH Tornado deposits, likely that exploiter had funds there from previous exploits.”
Grogan also observed that it’s uncommon for users to keep such large balances in privacy mixers, reinforcing the likelihood that the attacker was highly skilled and methodical.
StakeWise DAO Recovers $20.7M in Assets From Balancer Exploit
According to StakeWise DAO, its emergency multisig executed a series of on-chain transactions that successfully recovered approximately 5,041 osETH ($19 million) and 13,495 osGNO ($1.7 million) from the Balancer exploiter.
StakeWise DAO recovers $20.7 million from Balancer Exploiter. | Source: @stakewise_io on X
On the Ethereum mainnet, this recovery represents about 73.5% of the 6,851 osETH stolen earlier in the day. StakeWise noted that this was the maximum possible recovery, as the attacker quickly converted the remaining assets into ETH. All stolen osGNO were recovered in full.
StakeWise confirmed that the retrieved funds will be returned to affected users, distributed pro-rata based on their balances before the exploit. A complete post-mortem report and details on the next steps are expected to be published soon.
Security Best Practices Following the Balancer DeFi Exploit
In the aftermath of the attack, both users and developers should take immediate security measures.
Immediate Steps for Balancer Users
Before making any moves, users should confirm whether their funds were stored in Balancer V2 pools. Those potentially affected should:
Avoid interacting with compromised contracts or suspicious “recovery” links.
Wait for verified updates from Balancer before attempting withdrawals.
Use blockchain explorers or portfolio trackers to check for unusual transactions.
What Developers and Builders Can Learn from the Balancer Exploit
Developers using Balancer’s code or similar architectures should act swiftly to assess potential exposure. Key actions include:
Conducting comprehensive smart-contract audits with a focus on internal balance functions.
Isolating or disabling vulnerable contracts until fixes are confirmed.
Implementing multi-signature approvals and time-locked withdrawals for vault operations.
Expanding bug-bounty programs to incentivize early discovery of potential flaws.
Broader Lessons for DeFi Security
The Balancer exploit underscores the fragility of shared-code ecosystems within decentralized finance. While open-source collaboration fuels innovation, it also spreads vulnerabilities across multiple protocols.
As DeFi continues to evolve, enhanced security frameworks, real-time monitoring, and layered contract protections will be essential to preserving trust and protecting billions in total value locked (TVL).
The exploit specifically targeted Balancer V2. Other versions, including Balancer V3, are under review but have not been confirmed affected.
Can stolen funds be recovered?
At this time, recovery prospects remain uncertain. Unless the attacker’s wallets can be identified and frozen or funds are voluntarily returned, recovery is unlikely.
Are Balancer forks at risk?
Yes. Dozens of DeFi projects that forked Balancer’s code may share the same vulnerability. Immediate code audits are strongly recommended.
What should users with funds in Balancer pools do?
Users should verify their exposure, avoid using vulnerable pools, monitor official announcements, and secure any unaffected assets in safe wallets.
Disclaimer:
The information provided in this article is for informational purposes only. It is not intended to be, nor should it be construed as, financial advice. We do not make any warranties regarding the completeness, reliability, or accuracy of this information. All investments involve risk, and past performance does not guarantee future results. We recommend consulting a financial advisor before making any investment decisions.
Onkar Singh has three years of experience as a digital finance content creator. Throughout his career, he has collaborated with various DeFi projects and crypto media outlets. In his leisure time, he enjoys fitness activities at the gym and watching movies across different genres. Balancing his professional and personal interests, Onkar continues to contribute to the digital finance landscape while pursuing his hobbies.
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