• A malformed delegation transaction triggered a chain split by exploiting a deserialization bug from 2022.
• Major exchanges paused ADA services while development teams deployed emergency patches and restored network alignment
• The developer responsible admitted fault, while FBI involvement led to an IOG employee resigning over legal concerns.

Cardano experienced a critical network disruption on November 21 when a malformed transaction triggered a rare chain split. The incident stemmed from a known deserialization bug in the node software, first introduced in 2022. The disruption impacted the $14 billion blockchain, leading to exchange pauses, smart contract inconsistencies, and temporary market volatility. The network did not halt entirely, but for hours, two competing chains operated simultaneously. Cardano’s developer teams deployed emergency patches within hours, and the network reconverged naturally by the following day.

Malicious Transaction Bypassed Node Validation Checks

The issue began around 08:00 UTC, when a crafted delegation transaction bypassed newer node versions while older nodes rejected it. This created incompatible ledger states across the network. The transaction closely matched one observed on Cardano’s testnet the previous day. 

According to a report from Intersect, the incident was not random but instead followed prior test behavior. Block production continued across both chains, with some identical transactions appearing on both sides during the disruption. Major crypto exchanges reacted quickly by suspending ADA-related services. 

Coinbase had the longest service interruption, halting withdrawals and deposits from 12:15 UTC on November 21 to 02:10 UTC on November 22. Kraken, Upbit, and other platforms issued shorter pauses to monitor chain convergence. DeFi platforms on Cardano also suffered inconsistencies, as transactions landed on different chains. This caused failed or delayed confirmations, disrupting smart contract operations for users.

Emergency Patches Issued: Network Re-stabilizes as Developer Admits Fault

Development teams from Input Output Global, Cardano Foundation, Intersect, and EMURGO coordinated to respond to the issue. Emergency updates were released within three hours after detection. The network reconverged by November 22 as nodes realigned through Cardano’s consensus protocol. The ADA token price dropped up to 16% after the split but later regained partial ground. At the time of reporting, ADA trades near $0.41.

An individual identified as “Homer J” took responsibility for the transaction in a post on X. The user admitted to replicating the transaction from a personal challenge, relying on AI-generated instructions. They expressed regret and called the error careless. The user did not test on the testnet before submitting to the mainnet. In the statement, they accepted full responsibility and apologized to the Cardano community.

Charles Hoskinson stated publicly that the act was intentional and labeled it a personal attack. He confirmed that law enforcement, including the FBI, had been contacted. A fact sheet from Intersect supported the claim that authorities had been notified regarding the transaction. An IOG employee known as “effectfully,” who worked on Plutus, announced their resignation following Hoskinson’s FBI involvement. They cited concerns about future legal consequences for developers making technical mistakes.