Monero Faces Reported 51% Attack as Qubic Controls Over 52.36% Hashrate

Monero (XMR) is currently under a reported 51% attack following claims that the Qubic mining pool has taken control of over 50% of the network’s hashrate. According to reports, the Qubic team briefly controlled as much as 52.36% of Monero’s mining power, with some online claims suggesting a hashrate of 2.65 GH/s or even surpassing 53% [1]. The attack has raised significant concerns about the integrity of Monero’s decentralized structure and the security of its proof-of-work (PoW) consensus model. A major chain reorganization was detected on August 8, 2025, marking a critical moment in what many perceive as a demonstration of economic control over the network [2].

The Qubic project, led by IOTA co-founder Sergey Ivancheglo, has framed the attack as an “economic demonstration” rather than a malicious act. The team reportedly uses an incentive model to attract miners by offering QUBIC tokens as rewards, which are then exchanged for stablecoins and used to buy more QUBIC tokens, creating a self-sustaining economic loop that supports its hashrate dominance [3]. While the team asserts it has no intention of disrupting the network, the ability to reorganize blocks, censor transactions, or facilitate double-spending remains a serious threat to Monero’s trust model [4].

The economic implications of the attack are significant. The price of XMR dropped by approximately 8% in the wake of the news, while QUBIC tokens gained 4% in value [5]. Analysts have pointed out that maintaining such a high hashrate is extremely costly. Charles Guillemet, CTO of Ledger, estimated the daily cost of sustaining such control at roughly $75 million [6]. This raises questions about the long-term viability of the attack and whether it is driven by economic incentives rather than malicious intent.

Despite the reported control by Qubic, there is debate within the community about the true extent of the attack. Some users argue that the dominance is overstated, citing data from MiningPoolStats which shows that the two largest pools processed 44 of the last 100 Monero blocks [7]. Others, including SeraiDEX lead developer Luke Parker, have questioned the success of the attack, noting that if it were fully effective, no blocks would have been mined by other participants [8]. Additionally, user tuxsudo raised concerns that Qubic may have disabled its hashrate API to obscure its true influence [9].

The incident has reignited broader discussions about the risks of hashrate centralization in proof-of-work systems. Monero, which prides itself on privacy and decentralization, now faces scrutiny over its ability to maintain network integrity in the face of such an attack. Analysts suggest that protocol adjustments or increased diversification of mining resources may be necessary to prevent future exploitation [10]. The event also highlights the importance of decentralized mining pools and the need for robust mechanisms to detect and respond to 51% attacks.

As the situation evolves, the Monero community is being called upon to act swiftly and cohesively to address the vulnerabilities exposed by the Qubic pool’s actions. The outcome of this incident may have lasting implications not only for Monero but for the broader cryptocurrency ecosystem, as it underscores the fragility of blockchain security in the face of concentrated mining power.

Source: [1] https://coinmarketcap.com/community/articles/689b5dd8668f434552362df5/

[2] https://www.coindesk.com/business/2025/08/12/qubic-claims-majority-control-of-monero-hashrate-raising-51-attack-fears

[3] https://www.ainvest.com/news/monero-faces-critical-51-attack-qubic-controls-network-hash-power-2508/

[10] https://www.onesafe.io/blog/monero-51-percent-attack-lessons-strategies