Monero Faces Looming 51% Attack Threat as Qubic's Hashrate Surpasses 26.96%

Monero (XMR), the leading privacy-focused cryptocurrency by market cap, faces a potential 51% attack threat from rival blockchain Qubic starting August 2. Qubic, a layer one (L1) project founded by Sergey Ivancheglo (CFB), plans to leverage its “Useful Proof of Work” (uPoW) system to simultaneously secure its network and mine Monero. This system allows Qubic’s “AI miners” to utilize idle computational cycles for XMR mining, with rewards converted to USDT to buy and burn QUBIC tokens, creating a deflationary model. Since May 2025, Qubic’s integration has drawn significant Monero mining power, with its hashrate share fluctuating between 20-40% in July, nearing levels that could trigger a 51% attack [1].

As of July 27, 2025, Qubic reportedly controls 26.96% of Monero’s 6.12 gigahash per second (GH/s) hashrate, a figure Monero advocates allege is artificially inflated through “spoofing.” A 51% attack could enable double-spending, transaction censorship, or orphaned blocks, potentially eroding trust in Monero’s privacy-centric reputation. Redditors on the r/monero subreddit have urged immediate action to prevent such an outcome [1].

CFB has framed the operation as a demonstration of uPoW’s viability, not an attempt to destabilize Monero. He has advised exchanges to require 13 XMR transaction confirmations instead of 10 during the test period, suggesting the move is economically beneficial rather than malicious. Qubic supporters argue that uPoW’s integration validates its technology, while critics warn of parasitic network behavior. The Monero community remains divided: some advocate migrating to decentralized pools like P2Pool, while others propose protocol adjustments to counter the threat [1].

Past threats, such as the 2022 MineXMR incident, were mitigated through decentralization efforts and pool migration. However, Qubic’s sustained hashrate near critical thresholds represents a new challenge. Analysts note that a successful attack could undermine Monero’s credibility, potentially pushing users to alternatives like Zcash or Zano. Conversely, if Qubic’s test proceeds without causing chaos, it may reinforce uPoW’s appeal. Neutral observers view the situation as a stress test for both projects and proof-of-work’s vulnerabilities [1].

As of July 27, Qubic has not yet sustained 51% control, but its hashrate remains volatile. The outcome will likely influence debates around mining centralization and the future of privacy-centric cryptocurrencies.

Source: [1] [Monero Faces Looming 51% Attack Threat From Rival Blockchain Qubic] [https://api.news.bitcoin.com/wp-json/bcn/v1/post?slug=monero-faces-looming-51-attack-threat-from-rival-blockchain-qubic]