Monero, the largest privacy-focused cryptocurrency by market capitalization, is facing a rare and serious mining security challenge. According to the reported plan, rival project Qubic intends to begin an effort on Aug. 2 to control more than 51% of Monero’s mining hashrate, with the campaign potentially running through Aug. 31. If successful, such dominance could theoretically open the door to double-spending, transaction censorship, and orphaned blocks, putting fresh attention on the limits of proof-of-work security when hashpower becomes concentrated.
Qubic’s uPoW Model Is Pulling in Monero Miners
Qubic founder Sergey Ivancheglo, also known as CFB, recently signaled the planned “51% attack” on social media. He framed the effort as a demonstration of Qubic’s Useful Proof of Work (uPoW) system rather than an attempt to destroy Monero. Under Qubic’s model, its so-called AI miners can secure the Qubic network while also mining Monero during idle cycles. The resulting XMR is then converted into USDT, which is used to buy back and burn QUBIC tokens, creating a deflationary incentive loop.
That integration has reportedly been active since May 2025 and has already drawn meaningful mining power from the Monero ecosystem. In July, Qubic’s share of Monero’s global hashrate reportedly fluctuated between 20% and 40%. As of July 27, 2025, Qubic was said to control about 26.96% of Monero’s total hashrate, while the network itself stood near 6.12 GH/s. Although this remains below the 51% threshold, the level has been high enough to trigger visible concern across the Monero community.
Community Fears Focus on Trust and Transaction Safety
Monero advocates warn that if a single entity were to maintain majority hashpower, confidence in Monero as a privacy-preserving transaction network could be damaged. Some community members have also accused Qubic of overstating its “self-reported” hashrate or spoofing figures, while arguing that the project is effectively parasitizing Monero’s mining base. Users on Reddit have urged the community to take the issue seriously before the threat becomes more than hypothetical.
This is not the first time Monero has faced concerns around mining concentration. In 2022, similar worries emerged around MineXMR, and the situation was eased through decentralization efforts and calls for miners to switch pools. In the current episode, some Monero supporters are again urging miners to move toward more decentralized options such as P2Pool, while others believe protocol-level changes may need to be considered.
A Broader Stress Test for Both Networks
CFB has also advised exchanges to temporarily require 13 confirmations for XMR deposits instead of 10 during the planned test period. Qubic, however, maintains that the initiative is meant to prove the economic value of uPoW rather than inflict damage, and argues that Monero’s unique privacy properties should help preserve its market appeal. Supporters of Qubic have echoed that view, presenting the move as a live validation of the project’s mining model.
From a wider industry perspective, the standoff could become a public stress test of both proof-of-work vulnerabilities and network resilience. If Qubic fails to secure lasting majority control, or if no major disruption emerges even near the threshold, Monero may end up demonstrating stronger resilience than critics expect. If confidence weakens, however, some users may consider alternatives such as Zcash or Zano. As of July 27, Qubic had not achieved sustained 51% control over Monero, but its hashrate remained close enough to critical levels to keep the market watching closely.