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. source

🚨 Breaking: Qubic Completes Historic 51% Takeover Demonstration of Monero Network 🚨

1. On August 11, 2025, Qubic protocol successfully executed a planned 51% hashrate takeover of the Monero network, culminating in multiple blockchain reorganizations—fully validating the strength of its Outsourced Computations and Useful Proof of Work (UPoW) models.
2. Why it matters: •Proof-of-Power in action — Qubic’s attempt wasn’t hypothetical: it was a fully orchestrated stress test, executed publicly and resiliently, including recovery from a DDoS campaign. •Up to 3× more profitable — Mining via Qubic during its Monero experiment generated up to 3 times the profitability compared to standard Monero mining. •Security alert for Monero — Industry experts like Ledger’s CTO raised alarms over a potential live 51% attack, while Monero’s price dipped significantly in response.
3. Key stats & context: •Qubic’s Monero hashrate dominance exceeded 51%, peaking at 3.01 GH/s. •60 Monero blocks orphaned in 24 hours—a clear sign of selfish mining and reorg activity. •The experiment was announced publicly, giving Monero ample time to prepare—a marked contrast to stealth attacks.
4. Key takeaway:

Qubic’s tickchain + CPU mining + UPoW framework has moved from theory to undeniable proof of concept. This isn’t hype it’s a technical demonstration and economic mechanism that now actively influences how we think about blockchain security, decentralization, and AI-integrated computation. source