Cardano experienced a brief chain split on Friday due to an old code vulnerability, which went unnoticed possibly due to its "dormant" nature.

On November 23rd, as reported by Cointelegraph, due to a "format error" in a delegation transaction, the Cardano network experienced a temporary chain split on Friday. Delegation transactions refer to transactions where ADA is delegated to a staking pool. Although these transactions are valid at the protocol level, they can potentially lead to a code fault that affects network functionality. According to an incident report released by the Cardano ecosystem organization Intersect, this "format error" transaction exploited an old code vulnerability in the underlying software library of the Cardano blockchain, causing nodes to diverge in transaction processing and ultimately resulting in a network split. This vulnerability was caused by a staking pool operator named Homer J, who used AI-generated code to drive the transaction and has admitted responsibility for the network split. The staking pool operator was required to download the latest version of the node software to fix the issue and reintegrate the split chain into a single, coherent blockchain. This temporary split has sparked a debate within the Cardano community. Some believe that Homer J's actions helped expose a critical flaw, while others, such as Cardano founder Charles Hoskinson, have referred to it as an attack on the Cardano network, and the FBI has intervened in the investigation. One user sarcastically remarked, "No one noticed the Cardano network partition because no one uses it."