11 agosto 2025: il pool collegato a Qubic ha superato la soglia critica in alcune finestre operative su Monero, raggiungendo 63 blocchi su 122 e causando una riorganizzazione (reorg) di fino a 6 blocchi.
Following the event, some exchanges – including Kraken – have prudently suspended deposits in XMR, while the community has accelerated the migration towards P2Pool.
For details of the event in the media and for the technical context, see also the journalistic reconstruction and the literature on the phenomenon of selfish mining: the academic reference study on the subject Eyal & Sirer (2014).
According to the data collected by our on‑chain monitors and public dashboards ( for example xmrchain and MoneroBlocks ), in critical windows the pool reached a hashrate share consistent with 51.6% calculated over the 122 block window.
Abbiamo verificato dozzine di blocchi orfani e più riorganizzazioni fino a 6 blocchi; gli stessi indicatori mostrano che la pressione sull'allocazione della potenza di hash era concentrata in intervalli discontinui piuttosto che continui. Dati aggiornati al 27 agosto 2025.
Cosa è successo, in breve
51% threshold exceeded: in certain operational windows, the Qubic pool concentrated the majority of the hashrate and published a private chain to the detriment of the main network.
Deep reorganizations: up to 6 blocks replaced, with dozens of blocks left orphaned (stale).
Immediate impact: deposits in XMR suspended or slowed down on various exchanges and increase in confirmation requirements.
Economic dynamics: external incentives through buyback & burn of QUBIC have channeled a significant share of hashpower to Monero.
Spillover risk: the Qubic community has already indicated the intention to focus, in a subsequent phase, on Dogecoin – a PoW network with, according to updated market data, a market capitalization of about 35 billion dollars as of August 27, 2025.
Who is Qubic and why its incentive shifted the hashrate
Qubic is a Layer‑1 chain founded by Sergey Ivancheglo, known for his role in the IOTA ecosystem. The project adopts a Proof of Useful Work that, in addition to traditional PoW, directs computing power towards “useful” tasks – for example, processing artificial intelligence algorithms.
The focus is the economic model: with the buyback & burn mechanism, Qubic incentivizes mining on third-party networks. In practice:
The miners extract XMR on Monero and receive the usual rewards.
Le ricompense in XMR vengono convertite in USDT sul mercato.
With these funds, tokens QUBIC are purchased, which are partly burned and partly redistributed as a bonus.
The result is twofold: on one hand, it creates deflationary pressure on the QUBIC token; on the other, it offers an expected return for pool participants potentially higher than that obtainable with direct mining on Monero.
Not surprisingly, many CPU miners have recently focused their hashrate precisely on the Qubic pool. It must be said that the network’s response has moved in parallel.
Chronologia dell'escalation
Essential Timeline
May 2023: the contribution of the Qubic pool to Monero mining was marginal, below 2%.
End of July 2025: the pool’s share exceeds 25%, with peaks among the main players in the pool landscape.
August 11, 2025: Qubic claims operational windows with over 51% of the hashrate, applying selfish mining practices; in a window of 122 blocks, the pool produces 63.
Key Numbers
63/122 blocks produced in a critical window ( approximately 51.6% ).
Reorganization of up to 6 blocks into individual events, resulting in the formation of orphan blocks.
High concentration of hashrate on a single pool in specific time windows.
How a 51% attack works
Selfish mining, in simple words
Con il controllo di oltre il 51% della potenza di calcolo, un attore può trattenere i blocchi appena trovati costruendo una catena privata. Quando è vantaggioso, la catena privata viene pubblicata e risulta più lunga di quella pubblica, attivando la riordinazione delle ultime conferme.
In this way, some transactions can be excluded (censorship) or attempts at double spending can be made. In this context, the timing and strategy of publication make the difference.
Censorship and centralization: the risks
Selective censorship: some payments or transactions might be deliberately omitted.
Slower confirmations: in reaction to the attack, the exchange has increased the number of confirmations required to process transactions.
Fragilità strutturale: un'alta concentrazione di hashpower in pochi pool riduce la resilienza complessiva della rete.
Practical impact on users, merchants, and exchanges
Double spending: transactions already confirmed can be “rewritten” following the reorg.
Stale blocks: the increase in orphan blocks leads to an accumulation of pending transactions in the mempool.
Suspended or delayed deposits: in response to the attack, some platforms – as confirmed by Kraken – have temporarily suspended deposits in XMR.
The Qubic team admitted to using selfish mining techniques and operational windows in which their pool held over 51% of the hashrate. The episode prompted operators and infrastructures to tighten risk policies. An interesting aspect is the speed with which such measures were adopted.
Why the buyback & burn made the difference
Price and narrative: the purchase and burning operations of the tokens create a narrative of scarcity, capable of influencing the market value of the token.
Expected return: between bonus and potential appreciation of the QUBIC, the return for pool participants can exceed that of native mining.
Network effect: the entry of more miners increases the probability of producing blocks within the pool, fueling the cycle of incentives.
In essence, a well-structured external economic incentive can impact the security of a third-party PoW network, opening windows of vulnerability without the attacker having to invest in hardware dedicated to that specific network. It should be noted that not all networks react in the same way.
Community reactions and regulatory debate
The Monero community has moved on multiple fronts. On one hand, there has been an increase in migration towards decentralized mining solutions like P2Pool to strengthen the distribution of the hashrate; on the other hand, “contextual” measures have been adopted such as raising the number of confirmations required by exchanges and initiating discussions on possible consensus mitigations. Some developers have reiterated that a deep reorg does not prove a permanent control of the hashrate, but rather a period of predominance.
Ci sono anche stime non verificate che suggeriscono che mantenere un controllo totale e prolungato richiederebbe investimenti dell'ordine di decine di milioni di dollari al giorno, un punto discusso a livello di analisi del rischio.
The economic sustainability of a continuous attack thus remains a subject of debate and strongly depends on market dynamics, the liquidity of exchanges, and the conversion costs of the incentivizing token.
In parallel, the episode reignites the regulatory debate on privacy coin and the growing concentration of pools, fueling demands for greater operational transparency and, in some circles, for reforms aimed at promoting a wider distribution of hashrate.
Dogecoin in the spotlight: risk of inter-chain contagion
The Qubic community has expressed the intention to direct its efforts towards Dogecoin, a PoW network whose capitalization, according to the data reported by CoinMarketCap, currently exceeds 35 billion dollars as of August 27, 2025.
Se l'approccio "buyback & burn" e la concentrazione della hashrate venissero replicati, anche reti con mining congiunto o strutture di pool consolidate potrebbero affrontare pressioni simili. Il messaggio per il mercato è chiaro: gli incentivi in token possono diventare strumenti economici capaci di influenzare l'intera blockchain.
Realistic countermeasures for PoW networks
Decentralized pools: encourage and adopt solutions like P2Pool to reduce the risk of a single point of concentration.
Consensus parameters: evaluate temporary adjustments of the consensus parameters to disincentivize opportunistic hashrate coming from external sources.
Risk policy: increase confirmations for particularly sensitive transactions and promote coordination between exchanges, pools, and developers.
On-chain monitoring: implement alert systems to observe the distribution of hashrate, any reorgs, and abnormal rates of stale blocks; public dashboards like xmrchain assist collaborative monitoring.
Why this story matters
The Qubic–Monero case shows how the security of a PoW blockchain does not depend solely on hardware, but also on economic incentives and pool governance.
It is a change of perspective where "off-chain" remuneration models can, in certain windows, allow operational control over third-party networks. That said, the response capability of the community remains a decisive factor.
Nota editoriale: per alcuni dettagli tecnici – come specifici log di reorg e dichiarazioni ufficiali complete del team Qubic – sono necessarie ulteriori fonti primarie. Abbiamo collegato dashboard e fonti pubbliche; aggiornamenti aggiuntivi saranno integrati non appena saranno disponibili. Dati aggiornati al 27 agosto 2025.
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51% Attack on Monero: on August 11, 2025 Qubic signs 63 blocks out of 122 — buyback, reorg up to 6 b...
11 agosto 2025: il pool collegato a Qubic ha superato la soglia critica in alcune finestre operative su Monero, raggiungendo 63 blocchi su 122 e causando una riorganizzazione (reorg) di fino a 6 blocchi.
Following the event, some exchanges – including Kraken – have prudently suspended deposits in XMR, while the community has accelerated the migration towards P2Pool.
For details of the event in the media and for the technical context, see also the journalistic reconstruction and the literature on the phenomenon of selfish mining: the academic reference study on the subject Eyal & Sirer (2014).
According to the data collected by our on‑chain monitors and public dashboards ( for example xmrchain and MoneroBlocks ), in critical windows the pool reached a hashrate share consistent with 51.6% calculated over the 122 block window.
Abbiamo verificato dozzine di blocchi orfani e più riorganizzazioni fino a 6 blocchi; gli stessi indicatori mostrano che la pressione sull'allocazione della potenza di hash era concentrata in intervalli discontinui piuttosto che continui. Dati aggiornati al 27 agosto 2025.
Cosa è successo, in breve
51% threshold exceeded: in certain operational windows, the Qubic pool concentrated the majority of the hashrate and published a private chain to the detriment of the main network.
Deep reorganizations: up to 6 blocks replaced, with dozens of blocks left orphaned (stale).
Immediate impact: deposits in XMR suspended or slowed down on various exchanges and increase in confirmation requirements.
Economic dynamics: external incentives through buyback & burn of QUBIC have channeled a significant share of hashpower to Monero.
Spillover risk: the Qubic community has already indicated the intention to focus, in a subsequent phase, on Dogecoin – a PoW network with, according to updated market data, a market capitalization of about 35 billion dollars as of August 27, 2025.
Who is Qubic and why its incentive shifted the hashrate
Qubic is a Layer‑1 chain founded by Sergey Ivancheglo, known for his role in the IOTA ecosystem. The project adopts a Proof of Useful Work that, in addition to traditional PoW, directs computing power towards “useful” tasks – for example, processing artificial intelligence algorithms.
The focus is the economic model: with the buyback & burn mechanism, Qubic incentivizes mining on third-party networks. In practice:
The miners extract XMR on Monero and receive the usual rewards.
Le ricompense in XMR vengono convertite in USDT sul mercato.
With these funds, tokens QUBIC are purchased, which are partly burned and partly redistributed as a bonus.
The result is twofold: on one hand, it creates deflationary pressure on the QUBIC token; on the other, it offers an expected return for pool participants potentially higher than that obtainable with direct mining on Monero.
Not surprisingly, many CPU miners have recently focused their hashrate precisely on the Qubic pool. It must be said that the network’s response has moved in parallel.
Chronologia dell'escalation
Essential Timeline
May 2023: the contribution of the Qubic pool to Monero mining was marginal, below 2%.
End of July 2025: the pool’s share exceeds 25%, with peaks among the main players in the pool landscape.
August 11, 2025: Qubic claims operational windows with over 51% of the hashrate, applying selfish mining practices; in a window of 122 blocks, the pool produces 63.
Key Numbers
63/122 blocks produced in a critical window ( approximately 51.6% ).
Reorganization of up to 6 blocks into individual events, resulting in the formation of orphan blocks.
High concentration of hashrate on a single pool in specific time windows.
How a 51% attack works
Selfish mining, in simple words
Con il controllo di oltre il 51% della potenza di calcolo, un attore può trattenere i blocchi appena trovati costruendo una catena privata. Quando è vantaggioso, la catena privata viene pubblicata e risulta più lunga di quella pubblica, attivando la riordinazione delle ultime conferme.
In this way, some transactions can be excluded (censorship) or attempts at double spending can be made. In this context, the timing and strategy of publication make the difference.
Censorship and centralization: the risks
Selective censorship: some payments or transactions might be deliberately omitted.
Slower confirmations: in reaction to the attack, the exchange has increased the number of confirmations required to process transactions.
Fragilità strutturale: un'alta concentrazione di hashpower in pochi pool riduce la resilienza complessiva della rete.
Practical impact on users, merchants, and exchanges
Double spending: transactions already confirmed can be “rewritten” following the reorg.
Stale blocks: the increase in orphan blocks leads to an accumulation of pending transactions in the mempool.
Suspended or delayed deposits: in response to the attack, some platforms – as confirmed by Kraken – have temporarily suspended deposits in XMR.
The Qubic team admitted to using selfish mining techniques and operational windows in which their pool held over 51% of the hashrate. The episode prompted operators and infrastructures to tighten risk policies. An interesting aspect is the speed with which such measures were adopted.
Why the buyback & burn made the difference
Price and narrative: the purchase and burning operations of the tokens create a narrative of scarcity, capable of influencing the market value of the token.
Expected return: between bonus and potential appreciation of the QUBIC, the return for pool participants can exceed that of native mining.
Network effect: the entry of more miners increases the probability of producing blocks within the pool, fueling the cycle of incentives.
In essence, a well-structured external economic incentive can impact the security of a third-party PoW network, opening windows of vulnerability without the attacker having to invest in hardware dedicated to that specific network. It should be noted that not all networks react in the same way.
Community reactions and regulatory debate
The Monero community has moved on multiple fronts. On one hand, there has been an increase in migration towards decentralized mining solutions like P2Pool to strengthen the distribution of the hashrate; on the other hand, “contextual” measures have been adopted such as raising the number of confirmations required by exchanges and initiating discussions on possible consensus mitigations. Some developers have reiterated that a deep reorg does not prove a permanent control of the hashrate, but rather a period of predominance.
Ci sono anche stime non verificate che suggeriscono che mantenere un controllo totale e prolungato richiederebbe investimenti dell'ordine di decine di milioni di dollari al giorno, un punto discusso a livello di analisi del rischio.
The economic sustainability of a continuous attack thus remains a subject of debate and strongly depends on market dynamics, the liquidity of exchanges, and the conversion costs of the incentivizing token.
In parallel, the episode reignites the regulatory debate on privacy coin and the growing concentration of pools, fueling demands for greater operational transparency and, in some circles, for reforms aimed at promoting a wider distribution of hashrate.
Dogecoin in the spotlight: risk of inter-chain contagion
The Qubic community has expressed the intention to direct its efforts towards Dogecoin, a PoW network whose capitalization, according to the data reported by CoinMarketCap, currently exceeds 35 billion dollars as of August 27, 2025.
Se l'approccio "buyback & burn" e la concentrazione della hashrate venissero replicati, anche reti con mining congiunto o strutture di pool consolidate potrebbero affrontare pressioni simili. Il messaggio per il mercato è chiaro: gli incentivi in token possono diventare strumenti economici capaci di influenzare l'intera blockchain.
Realistic countermeasures for PoW networks
Decentralized pools: encourage and adopt solutions like P2Pool to reduce the risk of a single point of concentration.
Consensus parameters: evaluate temporary adjustments of the consensus parameters to disincentivize opportunistic hashrate coming from external sources.
Risk policy: increase confirmations for particularly sensitive transactions and promote coordination between exchanges, pools, and developers.
On-chain monitoring: implement alert systems to observe the distribution of hashrate, any reorgs, and abnormal rates of stale blocks; public dashboards like xmrchain assist collaborative monitoring.
Why this story matters
The Qubic–Monero case shows how the security of a PoW blockchain does not depend solely on hardware, but also on economic incentives and pool governance.
It is a change of perspective where "off-chain" remuneration models can, in certain windows, allow operational control over third-party networks. That said, the response capability of the community remains a decisive factor.
Nota editoriale: per alcuni dettagli tecnici – come specifici log di reorg e dichiarazioni ufficiali complete del team Qubic – sono necessarie ulteriori fonti primarie. Abbiamo collegato dashboard e fonti pubbliche; aggiornamenti aggiuntivi saranno integrati non appena saranno disponibili. Dati aggiornati al 27 agosto 2025.
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