According to CoinMeta, and based on an incident report published by classix, Ethereum Classic recently encountered a social engineering attack involving the core-geth client. An unreviewed version of ethereumclassic / core-geth v1.13.0 was released on September 14th and promoted as a "security update" through CoinMarketCap community updates and emails, enticing node operators to migrate to it. The report indicates that a small number of mining pool nodes did switch to this version, but they later reverted back to the long-term maintained etclabscore / core-geth v1.12.23. The incident did not result in any block losses, chain reorganizations, financial losses, or service interruptions. classix warns that this unreviewed version modified key logic such as chain selection and node discovery, posing a potential risk of causing a network split.