The Cardano blockchain experienced a brief split on Friday morning after a malformed transaction was validated by newer nodes but rejected by older ones. The incident, described by Charles Hoskinson as a deliberate attack by a disgruntled stake pool operator, led to the creation of two separate chains. Developers quickly addressed the issue with a hard fork and identified the attacker's wallet within a day. The disruption, which did not result in any downtime, was caused by a vulnerability in a software library that allowed the invalid transaction to be processed. The attacker, identified as Homer J., claimed the action was a test of the network and apologized for the unintended consequences. Despite the split, the Cardano network remained online throughout the incident.