Monero’s privacy-focused token climbed over 7% even as its blockchain suffered an 18-block reorg that reversed roughly 117 transactions and raised fresh concerns about the network’s stability.
The incident was carried out by Qubic — an AI-focused layer 1 blockchain and mining pool — which recently gained 51% of Monero’s hashrate and had already executed a six-block reorg last month.
This latest reorg began at block 3,499,659 on Sunday at 5:12 a.m. UTC and concluded at block 3,499,676 about 43 minutes later, according to Monero node operators who shared console data on X. The breach was later verified by cryptocurrency protocol researcher Rucknium on GitHub.
Despite the disruption, XMR’s price held steady through the reorg and, eight hours later, surged 7.4% from $287.54 to $308.55, according to CoinGecko. The rally came even as the broader crypto market slipped around 1% that same day.
Crypto podcaster xenu — one of the first to flag the reorg — suggested Qubic’s actions may have been an attempt to “stop the bleeding” in Monero’s price.
The reorg — described by xenu as the largest in Monero’s history — has sparked debate over the future of the privacy-focused blockchain.
The repeated attacks underscore the vulnerabilities of proof-of-work networks when they lack sufficient decentralization, raising doubts about their viability as reliable monetary systems.
“Personally, I don’t consider the Monero network reliable at this point. I’ll stop accepting XMR for payments until this situation is resolved,” crypto commentator Vini Barbosa wrote on X Sunday.
Centralization concerns emerge as a possible fix
According to researcher Rucknium, Monero node operators will “highly likely” begin using temporary Domain Name System (DNS) checkpoints — a method that lets nodes pull trusted block data from community-run DNS servers — as a safeguard against further reorgs.
But the approach comes with a trade-off: greater centralization. Some argue that Monero’s decentralization has already been compromised by Qubic’s control of more than half the network’s hashrate.
“If the Monero community fails to take block reorganizations seriously, this Sword of Damocles will continue to hang over its head,” warned Yu Xian, founder of blockchain security firm SlowMist, in a post on X.
Past attempts to defend against 51% attacks
The Monero community has previously debated changes to its proof-of-work consensus to reduce the risk of 51% attacks. Proposed ideas have ranged from localizing mining hardware and adopting merge mining with Bitcoin and other cryptocurrencies, to integrating Dash’s ChainLocks solution.
So far, none of these measures have been put into practice, leaving Qubic with considerable sway over the network. Monero’s 10-block lock mechanism — designed to shield transactions from reorganizations — also proved insufficient, as the latest 18-block reorg bypassed that safeguard, Rucknium noted.
Despite repeated breaches, XMR has shown resilience. Since reports of Qubic’s hashrate dominance emerged on July 28, the token has slipped just 5.85%.
