Cardano experienced a chain split due to an error in the delegated transaction format, with no loss of user funds

The Cardano blockchain split into two chains due to a software vulnerability triggered by a malformed delegation transaction.

The transaction was validated on the new version of the node but was rejected by the old version of the software, leading to a network fork. The Cardano ecosystem governance organization Intersect stated in an incident report that this "toxic" transaction exploited a flaw in the underlying software library, splitting the network into a "poisoned" chain that included the transaction and a "healthy" chain that did not. Co-founder Charles Hoskinson initially claimed it was a "premeditated attack," but later a user on X, Homer J., publicly admitted responsibility, stating that he acted carelessly while trying to reproduce the "bad transaction" and relied on AI-generated instructions. The user claimed there was no malicious intent and that he did not gain any financial benefit from it. Intersect confirmed that there were no user fund losses and that most retail wallets were unaffected. The price of ADA tokens fell by over 6% as a result of this incident.