Cardano Briefly Splits as Malformed Transaction Triggers Software Bug

On November 21, 2025, the Cardano blockchain experienced a brief but notable disruption when a malformed transaction triggered an old software bug, leading to a temporary chain split. While the issue was quickly resolved, this event serves as a reminder of how legacy code paths can still cause unforeseen problems in major proof-of-stake networks. The incident began when a delegation transaction containing flawed data was submitted to the network. This exploit leveraged a dormant bug within an underlying software library used by older node versions. While the transaction itself was valid at the protocol level, it triggered this unexpected outcome.