$14M Vanishes in Fresh Attack on Bitcoin-Based DeFi Protocol

ALEX Protocol, a DeFi platform built on Bitcoin’s Stacks layer, has suffered a second major breach—this time resulting in an estimated $14 million loss.

The incident comes just over a year after a previous attack drained $4.3 million via its cross-chain bridge.

Initial reports of suspicious activity began surfacing on social media, prompting the ALEX team to confirm a “security incident.” The project later followed up with a detailed post-mortem, while the official website remains offline for maintenance.

The exploit stemmed from a flaw in how failed transactions were handled on the Stacks network. The attacker reportedly manipulated the protocol’s inability to properly verify transaction failures, using rejected data to falsely authorize fund withdrawals.

Crypto security firm QuillAudits pegged the damage at around $14 million. Among the stolen assets were 63.5 units of wrapped Bitcoin variants (aBTC and sBTC). The incident also rattled the broader Stacks ecosystem, with the price of ALEX plunging over 50% and STX—the network’s native token—dropping around 10%.

Confusion briefly surrounded the peg stability of sBTC after data feeds showed a deviation in price. However, a Stacks spokesperson clarified that the token remains on-peg when using official oracle data.

While the attack was isolated to ALEX, other projects in the Stacks ecosystem responded swiftly. Pontis paused its bridge to safeguard liquidity, and Bitflow removed the affected liquidity pools to prevent further risk.

This isn’t ALEX’s first encounter with a critical vulnerability. In May last year, $4.3 million was drained from its XLink bridge, a breach believed to be tied to a compromised private key. Following that incident, the team implemented various security upgrades and migrated critical contracts—but clearly, those measures weren’t enough to prevent this far more damaging exploit.

Alexander Stefanov

With over 8 years of experience in the cryptocurrency and blockchain industry, Alexander is a seasoned content creator and market analyst dedicated to making digital assets more accessible and understandable. He specializes in breaking down complex crypto trends, analyzing market movements, and producing insightful content aimed at educating both newcomers and seasoned investors. Alexander has built a reputation for delivering timely and accurate analysis, while keeping a close eye on regulatory developments, emerging technologies, and macroeconomic trends that shape the future of digital finance. His work is rooted in a passion for innovation and a firm belief that widespread education is key to accelerating global crypto adoption.