SecondFi Stops Theft of 129 Million ADA After 16 Million ADA Lost in Three Wallet Attacks

SecondFi lost 16 million ADA worth $2.4 million from 374 user wallets in three separate attacks that exploited a flaw in its proprietary wallet generation software, CoinDesk reported on June 24. The vulnerability activates at the address level when a transaction is signed, leaving users unable to protect funds by moving seed phrases to other wallets.

SecondFi rolled out a patch for unaffected users and triggered emergency measures that secured a further 129 million ADA before attackers could reach it.

The rescued holdings were routed to a third-party custodian. An external accounting firm was engaged to verify those funds, and affected users must submit claims directly to SecondFi. Blockchain security firm SlowMist estimated that total losses could exceed $20 million once the full range of compromised wallets and tokens is accounted for, a figure that remains unconfirmed pending an independent audit.

Cardano founder Charles Hoskinson acknowledged the incident. "It hurts them whenever they lose anything," he said. " ADA was trading around $0.15 at the time of the report.