Monero Blockchain Hit by 18-Block Reorganization Erasing 118 Transactions

According to blockchain explorer data, Monero experienced its deepest chain reorganization, lasting 43 minutes and invalidating 118 transactions, raising concerns about network security and mining centralization.

XMR

Summary

Monero underwent its largest-ever blockchain reorganization on September 14, replacing 19 blocks between heights 3,499,659 and 3,499,678 and erasing 118 confirmed transactions. The event lasted about 43 minutes and highlighted potential vulnerabilities after mining pool Qubic reportedly seized over 51% of the network’s hashrate, enabling chain rewrites at an estimated cost of $100,000 per day. Users and exchanges reported invalidated transactions, while community members debated solutions such as localized mining or ChainLocks. Despite the disruption, Monero’s XMR token rose 7% intraday before settling at $305, marking weekly and monthly gains of 12% and 29%, respectively.

Terms & Concepts
  • Blockchain Reorganization: An event where the blockchain replaces a set of confirmed blocks with a new chain segment, potentially reversing transactions.
  • Monero (XMR): A privacy-focused cryptocurrency that uses advanced cryptography to keep transactions confidential and untraceable.
  • 51% Attack: A situation where a single entity controls over half of a blockchain network’s hashrate, allowing potential chain rewrites or double-spending.