On August 12, 2025, the Monero blockchain suffered a critical 51% attack as Qubic gained majority control of the network's hash rate. Sergey Ivancheglo (CFB) of Qubic announced the takeover on X, stating: "Looks like Qubic has achieved 51% over Monero", a claim later confirmed by Ledger CTO Charles Guillemet.
Guillemet warned that Qubic's dominance allows it to orphan competing blocks, enabling large-scale blockchain rewrites, double-spending, and transaction censorship. He estimated the attack costs $75 million daily but noted profitability is possible short-term due to Monero's $6 billion market cap versus Qubic's $300 million valuation. Monero's recovery options are limited, with Guillemet declaring a full takeover "possible and even likely".
Qubic implemented a "pay-to-switch" strategy, offering miners $3.13/day versus standard pools' $0.64, driving Monero's hash rate to 3.01 GH/s. This contributed to XMR's 28% price drop over 30 days, while QUBIC surged 57%. Qubic allocates 50% of mining profits (∼$59,000 daily at current prices) to burn QUBIC tokens. Following the attack, XMR plunged 13% to $247.
CFB claimed the attack aimed to "help Monero prepare for future fights" against three-letter agencies, though this contradicts security experts' warnings of irreversible network damage.
