Cardano Blockchain Faces Temporary Chain Split on November 20

The Cardano blockchain network experienced a temporary chain split on November 20, triggered by a malformed delegation transaction that exposed a software vulnerability and divided the network into parallel ledgers. The incident, which affected node operations but resulted in no loss of user funds, prompted a swift coordinated response from developers and operators to restore uniformity.

According to a postmortem report from Intersect, the Cardano ecosystem's governance organization, the split occurred when newer node versions accepted the invalid transaction while older versions rejected it. This disagreement exploited a known bug in an underlying cryptographic library, first identified on the Preview testnet in 2022, leading block producers to build on separate chain branches. One branch incorporated the "poisoned" transaction, while the other remained healthy. Block production continued throughout, albeit at a reduced pace, and user interfaces displayed inconsistencies as the divergence propagated.

Stake pool operators and node runners were immediately instructed to upgrade to version 10.5.3 of the node software, a hotfix developed overnight by engineers from Input Output,...