Cardano experienced a chain fork due to an incorrect transaction format, but no user funds were lost.

According to Mars Finance, the Cardano blockchain split into two chains due to a software vulnerability triggered by a malformed delegated transaction. The transaction passed verification on newer nodes but was rejected by older software versions, causing the network fork. Intersect, the Cardano ecosystem governance organization, stated in its incident report that this "toxic" transaction exploited a vulnerability in the underlying software library, splitting the network into a "poisoned" chain containing the transaction and a "healthy" chain not containing it. Co-founder Charles Hoskinson initially claimed it was a "premeditated attack," but subsequently, a user named Homer J. publicly admitted responsibility, stating that he was negligent in attempting to reproduce the "bad transaction" and relied on AI-generated instructions. The user stated that he had no malicious intent and did not gain any financial benefit from it. Intersect confirmed that no user funds were lost, and most retail wallets were unaffected. The price of the ADA token fell by more than 6% as a result of the incident.