Monero faces the risk of a 51% attack from the competitor Qubic.

Monero (XMR), the largest large-cap privacy-focused cryptocurrency in the market, is facing an unprecedented threat as the rival blockchain project Qubic claims it will attempt to control over 51% of Monero's mining hashrate, starting from August 2.

The Monero community faces a new challenge.

Sergey Ivancheglo (CFB), the founder of Qubic and also a co-founder of IOTA, hinted on social media X about a plan for a 51% attack on the Monero network. According to the disclosure, this campaign will last until August 31, and could lead to the risk of double-spending (chi tiêu hai lần), transaction censorship, or the creation of orphan blocks. However, CFB claims this is a technology experiment "Useful Proof of Work" (uPoW) by Qubic and not intended to disrupt Monero.

The uPoW mechanism of Qubic and its relationship with Monero

Qubic is a layer-1 blockchain built on an AI mining system (AI miners), allowing for the protection of the Qubic network while mining Monero during idle time. The XMR obtained will be converted to USDT and used to buy and burn QUBIC tokens – creating a profitable deflationary model. This mechanism has been implemented since May 2025, and has since attracted a significant portion of Monero's mining capacity.

In July, the global hashrate controlled by Qubic fluctuated between 20% and 40%, reaching a threshold that caused concern within the Monero community. As of July 27th, Qubic accounted for approximately 26.96% of the total hashrate of Monero, achieving 6.12 GH/s.

Some people in the community accuse Qubic of inflating its mining capacity ( "spoofing" ) and parasitizing on the Monero network. They warn that if Qubic actually achieves 51%, the reputation of Monero – which is a large-cap cryptocurrency commonly used for private transactions – could be severely damaged.

"We need to seriously consider this issue, don't wait until it's too late to act," a user on the r/monero forum wrote.

Some supporters of XMR believe that the hashrate of Qubic is being faked.### Internal division and future prospects.

Similar threats in the past, such as the MineXMR incident in 2022, were addressed by encouraging the community to switch to decentralized mining pools. CFB has also advised exchanges to require confirmation of 13 blocks instead of 10 blocks to reduce the risk of attacks during this testing phase.

Qubic believes that they are bringing "economic incentives" rather than destruction, and that the unique security features of Monero will help maintain the value of this coin. Supporters of Qubic see this as an opportunity to demonstrate the effectiveness of uPoW technology.

However, the Monero community is still divided. Some call for a shift to using decentralized mining pools like P2Pool, while others propose changes to the protocol. Some neutral observers believe this is a "test of endurance" for both Monero and Qubic, as well as illustrating the risks of the proof-of-work consensus mechanism.

A scenario presented is that if Qubic successfully takes control without causing harm, it will serve as proof of the effectiveness of uPoW. However, if it leads to chaos, Monero can demonstrate its resilience – even while facing short-term price volatility.

As of the end of July 27, Qubic still did not hold 51% of the hashrate of Monero, but the level of control had approached a dangerous threshold.

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