Cardano splits in two after bug exploitation, FBI involved

Cardano co-founder Charles Hoskinson said the Federal Bureau of Investigation (FBI) was involved after a developer exploited a sleeper node bug that split the $14 billion blockchain in two.

The split occurred on November 21 after a developer by the username Homer J of

“It started as a personal challenge ‘let’s see if I can reproduce the bad transaction’, and then I was stupid enough to rely on the AI’s instructions on how to block all incoming/outgoing traffic from my Linux server without properly testing it on testnet first,” the developer wrote in an X thread after the incident.

“I felt terrible as soon as I realized the magnitude of what I had caused,” the person said. “I know there’s nothing I can do to make up for all the pain and stress I’ve caused over the last X hours.”

Hoskinson says feat ‘was absolutely personal’

Hoskinson rejected the claim that it was an accident. He said the developer’s exploitation of the node bug “was absolutely personal” and that the person was “just trying to backtrack because they know the FBI is already involved.”

Cardano works so fast that we forked, fixed, and caught the guy in one day. He was very active in the Fake Fred discord. It was absolutely personal and now he’s trying to backtrack because he knows the FBI is already involved.

– Charles Hoskinson (@IOHK_Charles) November 21, 2025

“There was a premeditated attack from a disgruntled SPO who spent months in the Fake Fred discord actively looking for ways to damage IOG’s brand and reputation,” Hoskinson said. “He targeted my personal pool and this led to disruption of the entire Cardano network.”

Cardano blockchain splits in two as validators fail to reach consensus

The Cardano ecosystem organization project, Intersect, said in a report that the incident occurred around 8:00 a.m. UTC on November 21 when Homer J exploited “a bug in an underlying software library that was not caught by the validation code.”

Specifically, it took advantage of a bug in the deserialization of a hash, which the company says dates back to 2022.

With this bug, the developer was able to introduce “an oversized hash into a malformed delegation transaction to pass initial validation checks when it should have been rejected.”

“Previous versions of the ledger and usual transaction submission tools had hidden this bug, meaning it was only triggered in recent versions of nodes and using specialized tools,” Intersect said.

“Executing this transaction caused a divergence in the blockchain, effectively splitting the network into two separate chains: one containing the “poisoned” transaction and a “healthy” chain without it.

What raised suspicion that this was a pre-mediated attack was the fact that the exploit was used on the Cardano testnet just a day before the mainnet incident, according to Intersect.

After the incident, the Cardano team and various other ecosystem partners quickly resolved the issue, according to Hoskinson.

Cardano Blockchain Reportedly Business as Usual, But Trading Was Hesitant

Intersect said in its report that the Cardano blockchain continued to operate during the incident and added that block production continued on both chains while the network was split.

Major exchanges, including Coinbase, suspended ADA deposits and withdrawals while they monitored which chain would gain consensus, while DeFi protocols and explorers briefly showed conflicting network states.

Coinbase documented the longest disruption and suspended withdrawals and deposits from 00:15 UTC on November 21 to 02:10 UTC on November 22. Other exchanges, including Upbit and Kraken, have implemented shorter pauses.

Meanwhile, blockchain explorers had shown conflicting information during the partition. Decentralized finance (DeFi) protocols also experienced an inconsistent state during the split, with some smart contract interactions taking place on one chain while associated transactions landed on the other.

Some users have also reported increased transaction times. Usually, transactions on Cardano are executed within seconds. However, the split saw several transactions take several minutes to execute on-chain.

ADA price plunged as much as 16% following the news before stabilizing. It’s meup more than 1% in the past 24 hours to trade at $0.4130 as of 3:38 a.m. EST, data CoinMarketCap broadcasts.

ADA Price (Source: CoinMarketCap)

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