Cardano News Today: Cardano's Chain Split: FBI Probes "Attack" as Developer Laments Negligence

The Cardano blockchain experienced its first major chain split in eight years on November 21, 2025, after a malformed delegation transaction exploited a three-year-old software bug, prompting FBI involvement and an emergency response from developers. The incident temporarily divided the $14 billion network into two competing chains, causing confusion among users, exchanges, and DeFi protocols. Cardano co-founder Charles Hoskinson labeled the event a "premeditated attack" by a disgruntled stake pool operator, while the individual responsible—a developer who identified themselves as "Homer J" on X—claimed it was a careless mistake made while following AI-generated instructions.

The chain split began around 08:00 UTC when a transaction bypassed validation checks on newer node versions but was rejected by older ones, creating incompatible ledger states according to reports. Intersect, a Cardano ecosystem governance body, reported that the flawed transaction exploited a deserialization bug in a core software library, a flaw that had existed since 2022. Block production continued on both chains, with some transactions appearing on both versions, though confirmations slowed or failed as the network struggled to reconcile the divergence. Major exchanges, including Coinbase, Kraken, and Upbit, paused ADA deposits and withdrawals for up to 14 hours to mitigate risks.

ADA's price plummeted as much as 16% during the crisis, exacerbating a broader two-week decline that saw the token lose over 30% of its value. Charles Hoskinson, while insisting the core protocol was not compromised, emphasized the incident's impact on users, including lost staking rewards and inconsistent DeFi operations. He also announced that the FBI and other authorities were investigating the event as a potential cyberattack, citing links to a former participant in Cardano's Incentivized Testnet program.

The developer behind the erroneous transaction, Homer J, issued a public apology, stating they had attempted to replicate a problematic transaction as a personal challenge but failed to test it on a testnet first according to reports. They denied financial motives, claiming they neither sold ADA nor collaborated with others. "I felt awful as soon as I realized the scale of what I caused," they wrote, acknowledging the "negligence" of their actions.

The crisis prompted an emergency response from Cardano's development teams, including Input Output Global (IOG), the Cardano Foundation, and EMURGO. Patches were deployed within three hours, and the network naturally reconverged by November 22 according to reports. However, the incident led to the resignation of an IOG employee, known as "effectfully," who cited fears of legal repercussions for future development errors.

While no user funds were lost, the event raised concerns about the risks of untested code in decentralized networks. Hoskinson's characterization of the incident as an intentional attack contrasted with Homer J's apology, highlighting tensions over accountability in open-source ecosystems. Intersect pledged a full retrospective review to prevent future incidents, as regulators and investors scrutinize the long-term implications for Cardano's security and governance.