Qubic Claims 51% Control of Monero Hashrate

Ivancheglo has described the move as a “stress test” intended to help the Monero community prepare for future security threats. However, the claim has sparked fierce debate among developers and blockchain security experts, many of whom are deeply concerned about the implications.

A 51% attack takes place when a single party or coordinated group commands the majority of a proof-of-work (PoW) network’s computing power. Such attacks have previously caused significant disruption to blockchains like Ethereum Classic, which suffered multiple chain reorganisations in 2020, leading to millions of dollars in losses. Bitcoin Gold and smaller networks like Verge have also been victims of similar incidents.

Monero, known for its robust privacy features and use of the RandomX algorithm—which is designed to favour CPUs and resist ASIC domination—has historically boasted strong resistance to centralised mining power.

Qubic’s approach, branded as “useful proof-of-work” (uPoW), diverts Monero mining rewards by converting XMR into USDT, which is then used to purchase and burn QUBIC tokens. This process acts as both a deflationary mechanism and a liquidity sink for the Qubic ecosystem.

Between mid-May and late July, Qubic’s share of Monero’s hashrate surged from below 2% to over 25%, and at times, it topped the rankings of mining pools.

Charles Guillemet, CTO of Ledger, warned on X (formerly Twitter) that Monero “appears to be in the midst of a successful 51% attack,” referencing signs of a major chain reorganisation. Others, including SlowMist founder Yu Xian, have voiced scepticism regarding Qubic’s economic model and long-term viability.

Regardless of whether Qubic’s actions represent a malicious takeover or a genuine stress test, Monero’s market has reacted poorly. The price of XMR has dropped 6.65% in the past 24 hours, extending losses to nearly 16% over the past week.