Monero Re-org & Qubic

It seems like there may have been a delibrate 6 block re-org on Monero $XMR from Qubic mining. The target time is 2 minutes, therefore the re-org length is quite small. However, it is not clear if there was a double spend attack or if this was just selfish mining, i.e. trying to earn more of the block rewards. It seems for now that there is no evidence this was a double spend attack.

Qubic did seem to have around 20% of the Monero hashrate for a while and they may have sold some coins for USD, to rent hashrate to temporally push the hashrate up to over 30%. Qubic has significantly less than 51% of the hashrate, but perhaps it has just above the 33% theoretical threshold, where selfish mining is profitable (Assuming the coin price does not crash). It is not clear what the Qubic objective is here, but they do have a token $QUBIC and they may want to try and push up the price of it. Other than that, the endgame is unclear, but the "attack" from Qubic may not be sustainable

We have heard no reports of a double spend attack @krakenfx @bitfinex @MEXC_Official Any news on this? As for exchanges who take Monero deposits, it might be a good policy to increase the number of confs required for a deposit.

Qubic have now published an article claiming they do control over 51% of the network hashrate (which we think is unlikley)

Qubic say the end goal is to takeover all the block rewards of Monero, which essentially means full and sustained selfish mining. It is not clear whether they can actually achieve that. If this can be achieved, the value of the coin may fall

https://qubic.org/blog-detail/historic-takeover-complete-qubic-miners-now-secure-monero-network

Qubic's press release

On Monday, August 11, 2025, history was made as the Qubic protocol successfully completed its attempt to dominate the Monero network.

After a month-long, high-stakes technical confrontation, Qubic reached 51% of Monero's hashrate dominance, successfully reorganizing the blockchain. This event marks a pivotal moment in the crypto industry, serving as the ultimate validation of Qubic's "Outsourced Computations" and "Useful Proof of Work" (UPoW) models.

What is Qubic?

Qubic is built for a purpose: to host a fully on-chain, decentralized AI model, AIGarth. To achieve that, the chain was designed to be extremely lightweight, running out of the RAM of its validators. It functions as its own operating system, features innovative Quorum consensus, and has the ability to utilize mining power for other purposes rather than wasting it on simple hashing (Useful Proof of Work). Becoming the fastest, certified blockchain in the world at 15 million transactions per second was not the primary goal but a byproduct of the architecture.

As a part of its Useful Proof of Work design, Qubic needed to implement the first stage of Outsourced Computations and test it in the wild.

The Experiment

The Monero mining initiative began as a proof of concept. In its initial phase, Qubic split its resources between mining Monero and training its AI, AIGarth. This approach has proved highly profitable. At one point it became nearly 3x more lucrative than direct Monero mining and also attracted a torrent of new compute power to the network.

The experiment was a strategic, and at times combative, application of game theory. The Qubic community, through a decisive vote, chose to restructure its reward mechanism, shifting from token buybacks to direct rewards for Computors (Qubic’s chain validators). This change served as a powerful economic incentive that drew miners away from other Monero pools, fueling the takeover push.

The Process

The path to Monday's success was a two-part battle. The first attempt at a pure 51% hashrate dominance was met with fierce resistance, including a sustained DDoS attack that Qubic's infrastructure weathered for over a week. This "hacker war" highlighted the resilience of Qubic’s decentralized network, which remained operational despite outages to peripheral services.

The final, successful push began on August 11th with the deployment of a more sophisticated Selfish Mining strategy. This technical tactic, which proved effective with slightly less and at times more than 51% of the total hashrate, involved the Qubic pool secretly mining blocks and withholding them. The sudden appearance of orphaned blocks on the Monero network in the days leading up to today was the tell-tale sign that Qubic’s strategy was working. This tactic allowed the Qubic pool to gain a disproportionate share of the block rewards and, ultimately, the network's consensus.

That said, the team has decided not to take over the protocol's consensus for the moment because of internal discussions on whether that would hurt Monero's price. A third-party data scientist will confirm the facts listed in this article. Per dkat, the lead developer of the Monero experiment:

dkat — 8/12/2025 7:43 PM in the period [3475729, 3475850] (window of 122 blocks) we have mined 63 blocks. Thus, it surpassed the KPI we put for ourself (51% blocks). Congrats @Miner-Notifications for the full reward! This info will be verified (probably by Shai from kaspa - who hate us a lot to be a fair referee) Someone in qubic team should write a scientific report about this event and put on arxiv for future ref

What Now?

With the takeover test now complete, the Monero network's core functionality remains intact. Its privacy, speed, and usability have not been compromised. However, the end goal is for the Monero protocol's security to be provided by Qubic’s miners. This way, the rewards would be funneled through Qubic’s pools, bringing higher profitability and creating a new, higher incentive landscape for Monero miners.

This historic event is a testament to the power of economic incentives and a smaller protocol’s ability to outmaneuver a much larger one. The Qubic experiment successfully proved three crucial theories:

Outsourced Computations are Viable: Qubic’s UPoW model is a proven, real-world technology capable of repurposing compute power for external tasks.
Incentives Dictate Consensus: Any Proof of Work blockchain can be attacked and controlled by providing superior economic incentives to its miners.

Infrastructure Resilience: Qubic's decentralized network demonstrated a remarkable ability to withstand and recover from sophisticated, sustained network attacks.
In a move that has rewritten the rules of blockchain competition, a $300 million market cap AI protocol has successfully asserted its dominance over a $6 billion market cap privacy giant. The implications of this event will resonate throughout the crypto industry, providing a blueprint for future interactions between protocols and a stark reminder that in decentralized systems, economic incentives are the ultimate arbiter of power.

And here's tuxsudo (on X) saying Qubic never hit 51%:

Qubic never actually hit 51% btw. Don't fall for it.

However they do have a large enough hashrate to perform multi-block re-orgs with their selfish mining strategy.

They disabled API hashrate reporting so that they could lie about it.

Keep mining and ignore the noise. source

158 sats \ 3 replies \ @anon 22h

What a shitcoin. It’s not that qubic has 51%… but the fact they generated so much hashrate so quickly.

If some no name practically unheard of shitcoin can cause this much doubt and destruction, with 6+ block reorgs from “mining” their made-up AI chain (that does what again?)

Monero is toast. Any company or business or heaven forbid government that wants to can easily rent the CPUs and reorg after 10 blocks and do a pretty good double spend.

Even 12, 14, 16 blocks or ~ 30 minutes of rented hash can completely wreck the network and “qubic” some small shitcoin ‘mining their own coin’ is well on their way to doing this.

What a disaster.

102 sats \ 2 replies \ @rafael_xmr 20h

A big increase in marketing does sound like it would increase its market exposure and attract more users, so their marketing play and everyone talking about them worked and the increase makes sense.

but it's still a nothing-burger for Monero, if it was this easy for anyone to "wreck it", it isn't getting any easier, a new player now would have to compete with all the current XMR miners, plus the Qubic attackers, driving up difficulty even further then each will have a smaller share of rewards and even less of a overall effect

0 sats \ 1 reply \ @Scoresby OP 20h

Does this mean you don't see this Qubic thing as a threat to monero?

102 sats \ 0 replies \ @rafael_xmr 5h

No because it's not sustainable in the long term and as we all know the money printer has its consequences

For starters their coin will go through a halving in a few days, slashing the mining subsidy in half, so they'll have half of the printed money to pump their scam and it won't be as attractive to miners anymore. And the coin is definitely not going up in price to make up for it

But Qubic alone may not be a threat but this period has indeed being an "annoyance" so it shows something to be fixed still and the community is discussing proposals to prevent this type of selfish mining in the future, but there is no urgency and no threat for now. https://github.com/monero-project/research-lab/issues/136

102 sats \ 1 reply \ @OT 12 Aug

Although I'm not so familiar with all the technical details of monero, I did spend a lot of time arguing with their community. One thing I thought was dumb was CPU mining. Like couldn't anyone just spin up a bunch of miners on old computers? And if everyday people can do that, then a data center could spin up 100k miners and destroy the network in a day.

It will be interesting to see how it plays out.

202 sats \ 0 replies \ @kepford 21h

I don't like to straw man stuff. I really try to avoid it but my experience with Monero people (fans of it at least) is that they don't really focus on economics or incentives. They don't really get game theory, or at least they don't seem to.

It could be that these people I've interacted with are just terrible at communication and logic. That is possible. But what is clear is that the main focus of Monero is privacy. This seems to me to be pointless if the system isn't secure from attack. I don't care if the network can be private but will be destroyed when it becomes worthy of attack.

But, what do I know. Maybe the project will come up with some useful things bitcoin can use. I have no desire to argue with people over it. If they wanna use it. Go for it.

0 sats \ 1 reply \ @claos545 17h

If Qubic’s claim is exaggerated — and they never actually sustained >51% hashrate then this is more marketing theater than a genuine “historic takeover.”

But even if it’s just selfish mining with ~33–40% hashrate, the implications are serious: it shows that Monero’s incentive model can be exploited without actually needing a textbook 51% attack. This blurs the line between “attack” and “opportunistic mining,” and that’s a much bigger long-term threat than one flashy press release.

The real takeaway here isn’t “Monero is dead” or “Qubic is king,” it’s that economic incentives will always win over ideology in Proof-of-Work. If a protocol makes it more profitable to mine elsewhere, miners will jump even if it risks the network’s health.

So whether this was 51%, 40%, or just smoke and mirrors, the lesson for Monero devs is the same: design incentives that keep your miners loyal, or someone else will.

0 sats \ 0 replies \ @rafael_xmr 5h

True, well said

0 sats \ 0 replies \ @BlokchainB 19h

Wow!

0 sats \ 0 replies \ @nitter 12 Aug bot

https://xcancel.com/BitMEXResearch/status/1955254320305217726