In a surprising twist for the world of cryptocurrency, Qubic, helmed by Sergey Ivancheglo, has claimed a potentially critical position by allegedly securing over 51% of Monero’s global hashrate. This development, disclosed on August 12, 2025, has sent ripples through the crypto community, as it raises the specter of a 51% attack on the privacy-focused blockchain. Ivancheglo, known for his previous role as a co-founder of IOTA, described the move as a stress test meant to fortify the Monero network against future threats. Nonetheless, this announcement has ignited a heated debate among developers and security experts over the implications for network security.
Unpacking the Implications
The concept of a 51% attack is not new. It occurs when one entity or group controls the majority of a network’s mining power, granting them the ability to manipulate transactions, censor users, and potentially double-spend coins. This could spell disaster for Monero, a project that has long championed decentralization and privacy, particularly given its use of the CPU-friendly RandomX algorithm designed to resist ASIC centralization. As explored in our recent coverage of Bitcoin’s mining difficulty adjustments, the challenges of maintaining network security are a constant concern in the crypto space.
Qubic’s strategy involves a “useful proof-of-work” (uPoW) model, which repurposes Monero mining rewards by converting XMR into USDT. These proceeds are then used to purchase and burn QUBIC tokens, thereby creating a deflationary mechanism that supports its ecosystem. From mid-May to late July, Qubic’s share of Monero’s hashrate surged from less than 2% to over 25%, occasionally topping pool rankings. Such rapid growth in hashing power concentration has raised alarms among the cryptocurrency community.
Charles Guillemet, CTO of Ledger, took to X (formerly Twitter) to voice his concerns, stating that Monero “appears to be in the midst of a successful 51% attack.” He pointed to signs of significant chain reorganization as evidence, a red flag that other industry experts are also wary of. Yu Xian, founder of security firm SlowMist, expressed skepticism about the sustainability of Qubic’s economic model.
Historical Context and Concerns
The potential for a 51% attack is not just theoretical. The cryptocurrency world has witnessed similar events before. Ethereum Classic suffered multiple reorganizations in 2020, which led to multimillion-dollar losses, while Bitcoin Gold faced similar challenges in 2018 and 2020. Even smaller networks like Verge have fallen prey to such attacks, highlighting the vulnerabilities that concentrated hashing power can expose in a network. For a deeper dive into the regulatory implications, see our coverage of the SEC’s latest guidance.
Monero has prided itself on resisting these kinds of threats through its unique algorithm and decentralized ethos. However, Qubic’s rapid ascension in hashing power poses a direct challenge to this narrative. The community is left grappling with whether this is a genuine attempt to stress-test and improve the network or a prelude to a more nefarious takeover.
Market Reaction and Future Implications
As the dust settles on this revelation, Monero’s market performance has taken a hit. The cryptocurrency has dipped by 6.65% in the past 24 hours, exacerbating a 16% decline over the last week. Such volatility reflects the uncertainty and fear gripping investors as they await clarity on Qubic’s true intentions.
Looking forward, the Monero community faces pressing questions about how to respond to this development. Can they adapt to safeguard against centralized control, or will this event mark a turning point in its decentralized mission? The answers will likely influence Monero’s trajectory and its reputation in the broader cryptocurrency landscape.
For now, the crypto world watches with bated breath, as the situation unfolds. Will Qubic’s actions serve as a catalyst for positive change, or will they expose vulnerabilities that could undermine Monero’s foundation? Only time will tell, but one thing is clear: the stakes have never been higher.
Source
This article is based on: Qubic Claims Majority Control of Monero Hashrate, Raising 51% Attack Fears
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Steve Gregory is a lawyer in the United States who specializes in licensing for cryptocurrency companies and products. Steve began his career as an attorney in 2015 but made the switch to working in cryptocurrency full time shortly after joining the original team at Gemini Trust Company, an early cryptocurrency exchange based in New York City. Steve then joined CEX.io and was able to launch their regulated US-based cryptocurrency. Steve then went on to become the CEO at currency.com when he ran for four years and was able to lead currency.com to being fully acquired in 2025.
