Concerns Arise Over a 51% Attack on Monero: uPoW Network Qubic Holds Majority Hashrate, but It’s Just a Test
Privacy Protocol Giant Monero Faces 51% Attack Concerns
The privacy protocol giant Monero has recently found itself in the midst of concerns over a 51% attack, as the Qubic mining pool claims to have gained control of over half of the network’s hashrate, leading the community into debates over the authenticity of this information and the underlying motives. This protocol, with a market capitalization of only $300 million, has successfully challenged a decentralized network worth over $4.6 billion, delivering a shocking blow to the understanding that “scale equals security” in blockchain.
Qubic Gains Majority Hashrate, Monero Network Security on Alert
Qubic founder Sergey Ivancheglo announced yesterday that his mining pool has acquired over half of Monero’s hashrate in a “controlled environment” and conducted a “51% takeover demonstration.” In theory, controlling the majority of the hashrate implies that Qubic can reorganize blocks, censor transactions, and even initiate double-spending attacks.
Monero appears to be in the midst of a successful 51% attack. The privacy-focused blockchain, launched in 2014 and long targeted by governments and three-letter agencies, is already banned from most major centralized exchanges. The Qubic mining pool has been amassing hashrate for… — Charles Guillemet (@P3b7_) August 12, 2025
Qubic has long attracted CPU participation in Monero mining through its “Useful Proof of Work” (uPoW) model, which subsequently converts the mined XMR into USDT for the repurchase and destruction of QUBIC tokens, creating its own deflationary economic cycle. The announcement indicated that Qubic did not directly engage in the hashrate battle but adopted a selfish mining strategy, requiring only 33% to 40% of the hashrate to gain a disproportionate advantage in block production. The method involves withholding newly mined blocks and mining the next one privately, releasing the longer chain once other miners’ work is completed on a shorter chain, causing their blocks to become orphaned.
Yuan Xian, founder of SlowMist, stated that the Monero network experienced six consecutive orphaned blocks during this demonstration, with the true objectives and economic benefits behind Qubic remaining unknown.
Is Qubic Truly in Control of 51% Hashrate? Doubts About Verifiability and Economic Feasibility
However, the community remains skeptical about whether Qubic truly maintains over half of the hashrate. After all, the publicly available hashrate data is solely sourced from Qubic’s own resource monitor, raising questions about its authenticity. Furthermore, mining six consecutive blocks is insufficient to prove control over the entire network, as the probability of achieving 20% to 30% hashrate already presents a high likelihood of doing so.
At the same time, Ledger’s CTO Charles Guillemet revealed that maintaining such a dominant position would require daily operational costs in the hundreds of thousands of dollars, along with a one-time hardware investment of approximately $75 million. Yuan Xian noted, “The authenticity of this matter is not easy to verify; to confirm exceeding 51%, one would need to initiate double-spending attack tests, preferably multiple times.”
A $300 Million Company Poses a Threat to a $4.6 Billion Giant: What is Qubic’s Purpose?
The crux of this offensive and defensive battle lies in the fact that a protocol with a market value of $300 million can pose a tangible threat to a privacy giant valued at $4.6 billion. Qubic officials emphasize that this action was not a malicious attack but rather an economic demonstration: “We exceeded Monero’s hashrate during this demonstration, showcasing the actual power of uPoW.” This proves that market scale itself cannot guarantee security, and this incident will help the community prepare for future potential threats.
Guillemet expressed concerns, stating that Qubic’s motives remain unknown: “Do they intend to seize control of Monero? Launch double-spending attacks? Or merely showcase their hashrate? The most worrisome aspect is the dark nature of Qubic’s motivations.”
Security Alarm: Provocation or Warning?
Although Qubic did not launch a double-spending attack against Monero, it has demonstrated the ability to reorganize the chain and isolate others from block production. It remains unclear whether this was simply a technical demonstration or a prelude to larger-scale attacks in the future. However, what is certain is that it has sounded the alarm for the crypto industry, signaling a threat known as “uPoW threat.”
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