Hacker Siphons $2.1M from Defunct Aztec Connect Privacy Bridge

A sophisticated attacker has successfully drained approximately $2.1 million from Aztec Connect, a privacy-focused Ethereum bridge that ceased operations three years ago, exploiting a critical vulnerability in code its developers can no longer patch.

The exploit targeted a proof-verification weakness in the abandoned RollupProcessorV3 smart contract, allowing the hacker to withdraw roughly 909 ETH along with other digital assets. Despite the protocol shutting down in 2021, residual funds remained locked in the deprecated infrastructure—funds that Aztec Labs, the original development team, lost administrative control over when they wound down the service.

Privacy bridges like Aztec Connect once offered users a way to obscure transaction histories on public blockchains, bundling multiple transfers into cryptographic proofs. However, the technology proved difficult to maintain at scale, leading many projects to pivot or shut down entirely. Aztec Labs has since shifted focus to building a privacy-centric Layer 2 network using zero-knowledge rollup technology.

The incident underscores a persistent risk in decentralized finance: orphaned smart contracts holding user funds with no ongoing security oversight. Once a protocol sunsets and developers relinquish admin keys—often a deliberate decentralization step—any undiscovered bugs become permanent attack vectors. Security researchers have long warned that deprecated DeFi infrastructure can turn into honeypots for skilled exploiters.

At current prices, the stolen Ethereum alone represents a significant haul. While blockchain forensics firms will likely trace the funds through mixing services, recovering assets from such exploits remains notoriously difficult without centralized intervention. The breach serves as a stark reminder for users to withdraw assets promptly when protocols announce shutdowns, and for developers to conduct thorough wind-down procedures including comprehensive audits of legacy code.

Based on reporting by the original source.