Cardano Network Experiences First Major Chain Split in Eight Years

TLDR

• Cardano network experienced a chain split on November 21 after a malformed transaction exploited a three-year-old bug in node software
• A developer named Homer J claimed responsibility, saying they relied on AI instructions and failed to test properly on testnet first
• Emergency patches were deployed within three hours and the network converged naturally by November 22
• Charles Hoskinson involved the FBI, calling it a premeditated attack, which led to an IOG employee resigning over concerns about future legal consequences
• ADA price dropped as much as 16% during the incident before recovering slightly, with exchanges pausing operations for up to 14 hours

Cardano experienced its first major chain split in eight years on November 21 when a developer exploited a three-year-old software bug. The incident temporarily divided the $14 billion blockchain into two competing chains.

The split began around 08:00 UTC when a malformed delegation transaction bypassed validation checks. Newer node versions accepted the transaction while older infrastructure rejected it. This created incompatible ledger states across the network.

The transaction exploited a deserialization bug that dated back to 2022. Evidence suggests the exploit was tested on Cardano’s testnet one day before being executed on the mainnet.

Despite the split, block production continued on both chains throughout the incident. At least some identical transactions appeared on both versions of the chain. Intersect, a Cardano ecosystem organization, emphasized that the network did not completely stall.

Major cryptocurrency exchanges responded by suspending ADA operations. Coinbase paused deposits and withdrawals for approximately 14 hours, from 12:15 UTC on November 21 through 02:10 UTC on November 22. Other exchanges including Upbit and Kraken implemented shorter pauses.

Block explorers froze or showed conflicting information during the partition. DeFi protocols experienced inconsistent states across the split. Transaction confirmation times, normally seconds on Cardano, stretched to minutes or failed entirely.

Emergency Response and Network Recovery

Development teams from Input Output Global, the Cardano Foundation, Intersect, and EMURGO coordinated an emergency response. Engineers deployed patches within three hours of detecting the issue.

The network converged through natural consensus by November 22. Independent stake pool operators, crypto exchanges, and engineers worked together to stabilize the chain. The recovery did not involve a centralized rollback.

Charles Hoskinson, Cardano’s founder, provided an official incident report addressing claims about the network. He confirmed that the mainnet never shut down and the core protocol was never compromised. The event was linked to an edge case in node implementation rather than a protocol failure.

An X user named Homer J publicly claimed responsibility for the chain split. The developer characterized their actions as a careless testing accident. They said they attempted to reproduce a bad transaction and relied on AI instructions without proper testnet verification first.

Legal Consequences and Developer Resignation

Hoskinson called the incident a premeditated attack and said the FBI was already involved. He rejected Homer J’s characterization of the event as an accident. Intersect confirmed that relevant authorities and law enforcement were being notified.

The decision to involve federal investigators prompted an IOG employee to resign. The developer, known as effectfully and identified as a Plutus language developer named Roman, expressed concern that future development mistakes could lead to legal consequences.

ADA’s price dropped as much as 16% following the incident before recovering slightly. The token currently trades at approximately $0.41. Intersect committed to conducting a full retrospective review and publishing a thorough report to prevent similar incidents.

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