What Actually Happened with the Cardano Exploit?
Cardano’s November 2025 chain split was triggered by a deliberately crafted malformed transaction that exploited an overlooked deserialization bug, causing newer and older node versions to disagree on its validity and resulting in two parallel ledger histories. Although block production never stopped, the network operated in a fragmented state for several hours, disrupting exchanges, block explorers, and DeFi applications, and producing delays and inconsistent data for users. The event prompted emergency patches, exchange suspensions, and a temporary drop in the ADA price, while also sparking controversy over intent after the individual responsible publicly apologized and Cardano leadership framed the incident as a possible targeted attack warranting FBI involvement. Beyond the immediate disruption, the incident raised broader concerns about validation consistency, software-version fragmentation, and the governance implications of treating developer mistakes as potential legal issues, prompting renewed focus on infrastructure upgrades and long-term resilience across the ecosystem.
