Monero Suffers 51% Attack as Qubic Dominates Network Hashrate

Monero (XMR) has become the latest high-profile victim of a 51% attack, with the Qubic mining pool seizing control of more than half of the network’s hashrate for a brief but critical period. This development has sparked alarm among developers, investors, and cybersecurity experts, who have long warned about the vulnerabilities of smaller, proof-of-work (PoW) blockchains to such attacks. The attack, confirmed by multiple industry sources, enabled Qubic to theoretically rewrite the blockchain, double-spend transactions, and censor blocks [1].

The event unfolded on August 12, 2025, when Qubic crossed the 51% hashrate threshold. While the pool’s founder, Sergey Ivancheglo, denied any malicious intent, stating that the move was meant to "protect Monero from hostile actors," the implications were clear. Analysts, including Charles Guillemet, CTO of Ledger, noted the economic impracticality of sustaining such a takeover, estimating the daily cost of maintaining the majority hashrate at $75 million [3]. This would not only cripple the network economically but also erode trust in the long-term viability of Monero.

The attack triggered immediate market reactions. Monero’s price plummeted by 10% in the first 24 hours, dropping from $276.69 to $251.35. A week later, on August 10, the coin had lost an additional 7 percentage points, with the XMR price standing at $234.98 as fears of network instability persisted [2]. Despite the rapid loss of control by Qubic—its hashrate falling below 14% after coordinated action by other miners—the damage to investor confidence was evident.

Monero, known for its strong emphasis on privacy and untraceable transactions, has long been a target of regulatory scrutiny. Governments worldwide have restricted its use on major centralized exchanges, labeling it a tool for financial crime. While privacy advocates continue to champion its anonymity features, the Qubic incident raises new concerns about the feasibility of maintaining decentralized consensus in smaller PoW-based networks [1].

Industry experts, including SlowMist founder Yu Xian, have pointed out that Qubic’s hashrate dominance had been building for months through aggressive miner incentives. However, the economic rationale for such a strategy remains questionable. Sustaining a 51% attack is not only costly but also self-defeating, as it undermines the value of the network itself.

Monero developers have yet to issue an official response, but the community is expected to push for structural reforms. Possible solutions include enhancing mining decentralization or exploring alternative consensus mechanisms. However, any changes must be carefully balanced to preserve the privacy-centric attributes that define Monero. The Qubic-led attack has reignited debates about the need for stronger network resilience without compromising the core principles that make Monero unique in the cryptocurrency landscape [2].

Source: [1] Monero rocked by successful 51% attack as Qubic pool seizes control, Crypto News, https://crypto.news/monero-rocked-by-successful-51-attack-as-qubic-pool-seizes-control/

[2] Monero Network Hit by Qubic-Led 51% Attack Attempt, Blockonomi, https://blockonomi.com/monero-network-hit-by-qubic-led-51-attack-attempt-xmr-price-dips/

[3] Coinpedia - Fintech & Cryptocurrency News Media | Crypto..., Coinpedia, https://coinpedia.org/