$128 Million Balancer Hack Affects Six Blockchains, Leads Berachain to Fork

A significant breach in the Balancer DeFi protocol resulted in over $128 million being stolen across six different blockchains. An access control flaw in Balancer V2’s smart contracts allowed unauthorized withdrawals, prompting Berachain to halt its operations to implement emergency security measures.

Key Takeaways

Hackers drained more than $128 million from six blockchains, with Ethereum losing the most at $99 million.
A flaw in the access control checks of Balancer V2's smart contracts enabled unauthorized withdrawals from boosted pools.

As November began, the crypto market faced a critical challenge when Balancer experienced a substantial exploit of $128 million on November 3. This attack highlighted a significant vulnerability in the protocol's security, draining funds and necessitating an unprecedented network halt by Berachain.

Balancer official post after confirming the hack

The hack is one of the largest decentralized finance (DeFi) breaches of 2025, occurring just as traders were hoping for a positive shift after disappointing performance in October.

Six Blockchains Targeted

On the same day, Balancer, particularly its V2 vaults and boosted pools, fell victim to a significant exploit. The attack stemmed from an access control vulnerability in its smart contracts that allowed the hackers to conduct unauthorized internal withdrawals. The breach affected multiple blockchains in a matter of hours.

Ethereum was the hardest hit, with losses totaling $99 million, which included large quantities of WETH, osETH, and wstETH. Other affected blockchains included Berachain with $12.86 million, Arbitrum at $6.86 million, BASE with $3.9 million, Sonic $3.44 million, Optimism at $1.58 million, and Polygon with $232,000.

List of chains affected in the Balancer hack

The breach impacted not just Balancer’s primary deployment; various protocol forks on separate chains inherited the same vulnerability. This compounded the attack surface, allowing hackers to drain funds from the entire ecosystem simultaneously.

Berachain's Urgent Response

In an uncommon reaction for blockchain networks, Berachain validators took emergency measures. They coordinated a network halt to address the exploit related to Balancer V2.

The official announcement stated, “The Berachain validators have coordinated to purposefully halt the Berachain network as the core team performs an emergency hard fork to address Balancer V2 related exploits on the BEX.”

Impact on Balancer’s Total Value Locked (TVL)

Following the exploit, Balancer's Total Value Locked (TVL) plummeted dramatically from around $443 million to $255.82 million, a nearly 50% decrease in a short period. The DeFi Llama chart illustrates this steep decline as users hurried to withdraw their funds to mitigate further losses.

Blancer V2 TVL after the hack

This mass exit reflects a significant loss of confidence in the security of the protocol, with even users with unaffected pools choosing to withdraw amid concerns about potential undiscovered vulnerabilities.

Overview of 2025's Hacking Incidents

The Balancer exploit now ranks as the third-largest crypto hack of 2025. Earlier in the year, North Korea's Lazarus Group reportedly stole $1.5 billion from Bybit, marking the largest theft in crypto history. In May, hackers drained $223 million from Cetus Protocol. Over the first half of this year, more than $2.17 billion has already been stolen, with notable incidents including Iran's Nobitex losing $90 million in June and India's CoinDCX losing $44.2 million in July.

Unlike single-exchange breaches, the $128 million loss from Balancer spanned six blockchains, emphasizing how a single vulnerability in forked protocols can lead to widespread damage across entire ecosystems.

A Challenging Start to November

The timing of this incident adds to the negativity surrounding market sentiment. October 2025 was expected to deliver the usual "Uptober" gains that traders look forward to, but instead, market conditions ended disappointingly, leading to one of the largest liquidations in history, with nearly $20 billion lost.

Now, as November begins, the crypto space is faced with one of the year's most significant DeFi hacks, further straining an already cautious market. The Balancer team has acknowledged the exploit and continues to investigate the matter.