Has Qubic successfully executed a 51% attack on Monero? As early as late July, rumors were circulating in the Monero community that the QUBIC mining pool was attacking Monero. Now, it seems QUBIC has succeeded.
On August 12, 2025, SlowMist tweeted that the Monero (XMR) network is suspected to have suffered a 51% attack. Monero recently experienced a chain reorganization with a depth of 6 blocks mined by an unknown pool. However, no pool on miningpoolstats.info has over 50% of the hash rate, suggesting this could be a covert malicious hash power attack or an accidental mining competition.
At the time of QUBIC's attack in late July, Monero's market cap was approximately $6 billion. As of now, XMR's market cap has dropped to about $4.6 billion, a decline of over 20%. Meanwhile, QUBIC's market cap is only around $2.3 billion. If QUBIC has indeed successfully controlled 51% of Monero's hash rate, we are witnessing a historic moment: a blockchain with a market cap of less than $300 million is taking over a $6 billion blockchain.
What exactly happened?
X user OrangeFren posted that Monero experienced a reorganization with a depth of 6 blocks. The 51% attack appears to have succeeded. If you are receiving XMR, wait for at least 10 confirmations.
Qubic founder Come-from-Beyond stated on social media: "It seems Qubic has achieved a 51% hash rate, surpassing Monero. We are awaiting confirmation from independent entities. Meanwhile, the Monero team is refining its 51% attack defense details. Many accuse us of being funded by three-letter agencies to attack this privacy coin. Now, what do you think after we've helped Monero prepare for future battles against such agencies?"
Of course, there are dissenting opinions. X user Luke Parker argued that 6 reorganizations do not necessarily mean a "successful 51% attack." In such cases, we would see infinite-depth reorganizations or no blocks mined by other pools (assuming the attacker censors other pools like this one). It does indicate that the high-hash-rate opponent got lucky.
Was Qubic just validating technology and seeking attention?
First, let’s understand Qubic.
Qubic was founded by Come-from-Beyond, a former co-founder of IOTA, a DAG-based blockchain. Qubic is a unique Layer 1 public chain with its core mechanisms being Useful Proof of Work (uPoW) and AIGarth. Traditional mining computations typically solve arbitrary puzzles, while Qubic converts computing power into real-world productivity—training its AI model, AIGarth. Here’s how it works: Miners contribute raw computing resources to Qubic's validators (called Computors). These Computors then use the hash power to train AIGarth directly in their memory, with all operations performed on-chain.
Qubic’s broader vision is to provide outsourced computing for the real world, inviting third parties like enterprises, universities, hospitals, and research labs to use AIGarth. Through customized smart contracts, these entities can connect, tailor the model to their needs, and even train specialized versions using Qubic’s computing network—like opening a decentralized supercomputer to the world, where collaborators can contribute and benefit without compromising security. However, this full vision is not yet realized, with key components (e.g., Oracle Machines for seamless data integration) still under development.
To demonstrate the feasibility of outsourced computing in real-world scenarios, Qubic conceived custom mining: Qubic provides hash power outside its network, redirecting part of its computing resources to external tasks like mining Monero or other PoW coins. Qubic also emphasized that the true potential of outsourced computing goes far beyond crypto mining.
Thus, in late July, Qubic began custom mining for Monero. Why start with Monero? Qubic stated that by entering the high-risk, competitive field of Proof of Work (POW) crypto mining, it could both validate its technology and attract industry attention.
How effective was it?
Qubic’s blog post revealed that before integrating Monero custom mining, CPUs accounted for only 10% of Qubic’s mining hash rate. Driven by higher profitability, this figure jumped to around 50% as more CPU miners joined the network. During the week of July 30 to August 7, Qubic’s peak hash rate reached 2.77 GH/s, equivalent to 50% of Monero’s global hash rate. A total of 4,285 Monero blocks were found, mining approximately 517 XMR + 6M XTM. The XMR, worth about $141,658, was sold—50% used for Qubic token buybacks and burns, and 50% to incentivize miners to contribute more CPU hash power. Qubic claimed its profitability for miners was about 3 times that of Monero, attracting many CPU miners to its network.
During this period, the Monero community launched DDoS attacks against Qubic, but with little effect.
On August 3, Qubic founder Come-from-Beyond stated that despite severe DDoS attacks, Qubic successfully mined 20% of Monero blocks...
On August 6, Qubic lead developer dkat noted on Discord: "I asked for quotes yesterday—around $500 per IP, 100Gbps bandwidth, lasting 24 hours, including SYN Flood and reflection attacks. So roughly $20,000 per day targeting all Qubic nodes and ecosystems. They’ve been DDoSing us for 7 days straight, so about $140,000..."
What’s next for Monero?
Based on multiple sources, the Qubic network may indeed control over 51% of Monero’s hash rate. This 51% attack, as Qubic stated, was to validate technology and attract attention. As promised, Qubic chose not to take over the Monero network. Its founder also hinted at future assistance to Monero against government agencies (e.g., FBI).
But for Monero, how can trust in the crypto community be restored? Is Qubic an enemy or a new ally? This remains to be seen.
