Cardano News Today: Monolith vs. Diversity: Cardano's 14-Hour Split Underlines Blockchain Design Risks

The Cardano blockchain experienced a rare chain partition on November 21, 2025, when a malformed delegation transaction exploited a dormant bug in its software library, splitting the network into two competing chains. The incident, which lasted approximately 14.5 hours, highlighted vulnerabilities in monolithic blockchain architectures and reignited debates about client diversity in protocols like Ethereum and Solana.

According to an incident report by Intersect, Cardano's ecosystem governance body, the transaction leveraged a deserialization flaw in hash-handling code introduced in 2022. The bug allowed a transaction with an oversized hash to bypass validation checks on newer node versions (10.3.x–10.5.1), while older versions rejected it. This discrepancy created two chains: one "poisoned" with the invalid transaction and a "healthy" chain without it. Stake pool operators and exchanges eventually upgraded to patched versions (10.5.2–10.5.3), reuniting the network.

The perpetrator, identified as a former stake pool operator known as "Homer J," admitted to crafting the transaction using AI-generated code as an experiment. He claimed no malicious intent but apologized for the disruption, which included frozen block explorers and potential double-spending risks. Cardano founder Charles Hoskinson, however, labeled the incident a "premeditated attack", noting the FBI had been alerted to investigate possible violations of the U.S. Computer Fraud and Abuse Act.

The split underscored the risks of relying on a single node implementation. While Cardano's Ouroboros proof-of-stake protocol preserved liveness-blocks continued to be produced on both chains-it sacrificed temporary uniqueness, creating a scenario Ethereum's multi-client advocates warn against. Ethereum, by contrast, runs multiple independent execution and consensus clients (e.g., Geth, Prysm), reducing the risk of a single bug causing a network-wide fork. In 2024, a Nethermind bug caused validators to miss rewards but did not trigger a split, demonstrating the redundancy of Ethereum's design.

Solana, which operates a single validator client, adopted a different approach: when its 2021 bot traffic overload caused a 17-hour outage, the network halted and required manual restarts. Cardano's incident, while less disruptive, revealed the trade-offs of its architecture. Unlike Solana's "halt-and-restart" model, Cardano's monolithic design allowed liveness to persist but created competing chains that required voluntary upgrades to resolve.

Post-incident analysis emphasized the need for rigorous testing of legacy code and expanded bug bounty programs. Intersect noted that the same exploit had appeared on Cardano's Preview testnet days earlier, providing a low-stakes warning. Critics argued that clearer disclosure pathways could have prevented Homer J from testing the exploit on mainnet, a move that Hoskinson condemned as "tampering with a digital economy"https://forklog.com/en/cardano-blockchain-experiences-split-due-to-transaction-error/.

The incident also raised questions about Cardano's market resilience. Despite the disruption, ADA's price fell modestly to $0.40 from $0.44, mirroring broader crypto market declines. Some users mocked the split's lack of public attention, quipping, "No one uses it," while analysts pointed to declining TVL and DeFi activity as signs of waning user confidence.

For Ethereum and Solana, the event reinforced the importance of client diversity. Ethereum's multi-client model, now a core design principle, aims to prevent single points of failure. Solana's reliance on a single client, meanwhile, remains a contentious trade-off between throughput and resilience. As blockchain protocols scale, the Cardano split serves as a cautionary tale: without redundancy, even minor bugs can expose systemic riskshttps://cryptoslate.com/cardano-split-in-two-by-a-single-transaction-lessons-for-eth-and-sol-client-diversity/.