Qubic Claims 51% Monero Hashrate Spur Security Fears

Monero’s network has been thrown into uncertainty after Qubic, a mining pool co-founded by Monero developer Sergey Ivancheglo, reportedly gained control of more than 50% of its hashrate. The claim, first made by CFB on August 12, suggested that Qubic had overtaken the network’s mining power, raising fears of a potential 51% attack. Ledger’s Chief Technology Officer, Charles Guillemet, echoed the concerns, stating that Qubic’s dominance could lead to malicious activities such as double-spending or chain rewrites [1].

The move was reportedly fueled by an aggressive “pay-to-switch” campaign, in which Qubic offered significantly higher mining rewards than traditional Monero pools. While standard pools yielded approximately $0.64 per day, Qubic’s rewards exceeded $3, attracting a substantial number of miners and pushing Monero’s hashrate to 3.01 GH/s [2]. The strategy led to a six-block reorganization and triggered a sharp drop in Monero’s price, with XMR declining nearly 9% in the immediate aftermath [3].

Qubic’s token, meanwhile, experienced a 57% surge in the same period, while Monero’s value fell by 28% over the previous month. Qubic’s profit-sharing model splits mining gains between participants and QUBIC token buybacks, with the potential to collect around 432 XMR daily—valued at approximately $118,000—while burning half of that amount each day [4].

Despite the alarming developments, CFB defended Qubic’s actions, claiming the move was a proactive measure to test Monero’s resilience against similar threats in the future. He denied any hostile intent, emphasizing that the maneuver was aimed at strengthening the network’s defenses [5]. However, the decentralized nature of Monero makes it difficult to confirm exact mining power distribution, as stealth hashing activity often evades public tracking tools [6].

The incident has reignited debates over the vulnerabilities of proof-of-work networks when mining power becomes overly concentrated. Analysts have pointed to the broader implications for privacy-focused cryptocurrencies, where security and decentralization are foundational. Cardano founder Charles Hoskinson highlighted the potential of alternative consensus mechanisms, such as Midnight, to prevent similar attacks in the future [7].

Monero’s core developers and the wider community are now working to assess the full impact of the hashrate shift and to explore potential safeguards. Whether Qubic’s actions constitute an attack or a stress test, the event has underscored the fragility of decentralized systems when faced with coordinated mining incentives. The long-term consequences may influence the development of new consensus protocols and governance strategies in the months ahead.

Source:

[1] Monero’s Network at Risk After Qubic Claims 51% Control (https://coinmarketcap.com/community/articles/689b7438a7fab86815903fc6/)

[7] Cardano Founder Highlights Midnight's Strength After ... (https://thecryptobasic.com/2025/08/12/cardano-founder-highlights-midnights-strength-after-monero-hit-by-51-attack/)