Monero (XMR), the privacy-focused cryptocurrency, has just gone through its biggest blockchain shake-up yet. On September 14, network monitors reported an 18-block reorganization that wiped out 118 transactions. Independent analyst Xenu called it “the largest reorg in Monero’s history,” raising fresh questions about how secure and reliable the network really is.
A blockchain reorganization happens when miners can’t agree on which version of the ledger is correct. The network just goes with the longest chain and drops the shorter ones.
In Monero, miners had to choose between chains, so some transactions that looked confirmed ended up getting canceled. This can cause problems like double-spending, slow transactions, and confusion for anyone taking XMR.
Qubic’s Mining Role
The episode has put the spotlight on Qubic, a rival blockchain project that controls a large portion of Monero’s mining power. Mining Pool Stats show Qubic controls 2.11 GH/s of Monero’s 6.00 GH/s hashrate, making it the largest single contributor. Earlier this year, critics accused Qubic of attempting a 51% attack on Monero.
Qubic founder Sergey Ivancheglo added to speculation with a post on X, stating Monero “will stay because Qubic wanted it to stay.” Analysts interpret this as a demonstration of influence rather than financial gain.
Xenu, citing Monero developer Sech1, noted that Qubic’s strategies, such as selfish mining, have caused inefficiencies, including a 43% orphan rate, reducing mining rewards.
Expert Warnings
Security experts warn the threat remains. Co-founder of SlowMist, posted, “If no one in the Monero community takes the issue of block reorganization seriously, then this Sword of Damocles will always hang over Monero’s head… It may not necessarily carry out a double-spend attack, but having this capability… It doesn’t even have to strictly exceed 51% of the hash power.”
Exchanges are responding cautiously. Kraken suspended XMR deposits and later raised required confirmations to 720, up from the usual 10, reflecting concerns about network trust.
The reorganization has already affected Monero’s market, contributing to past price drops of over 5% in 24 hours and more than 14% in a week during previous events. Analysts say repeated reorganizations could erode confidence in Monero if mining concentration is not addressed and stronger security measures are implemented.
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