Kraken suspended Monero deposits after detecting that a single mining pool gained majority control of the network’s hashrate.

The exchange cited security concerns following what appears to be a successful 51% attack on the privacy-focused blockchain.

“As a security precaution, we have paused Monero (XMR) deposits after detecting that a single mining pool has gained more than 50% of the network’s total hashing power,” Kraken announced Friday.

The exchange added that the concentration of mining power poses a potential risk to the network’s integrity.

Qubic, an AI-focused blockchain and mining pool, claimed it achieved 51% hashrate dominance over Monero following a month-long technical confrontation.

“After a month-long, high-stakes technical confrontation, Qubic reached 51% of Monero’s hashrate dominance, successfully reorganizing the blockchain,” Qubic representatives announced Tuesday.

Pool survives denial of service counterattack

While Monero community members initially denied the attack claims, mining pool statistics now confirm Qubic as the dominant Monero miner.

Qubic faced resistance during its takeover attempt, briefly falling to seventh place among Monero miners. On August 4, the pool suffered a denial-of-service (DDoS) attack, which significantly reduced its computational power.

The DDoS attack dropped Qubic’s hashrate from 2.6 gigahashes per second to just 0.8 GH/s, according to Sergey Ivancheglo, who claimed responsibility for the 51% attack. Denial-of-service attacks flood networks with fake traffic, disrupting legitimate operations.

Despite the counterattack, Qubic recovered its hashing power and accumulated enough computational resources to control majority network operations. Current mining statistics confirm Qubic’s position as the top Monero mining pool.

Kraken’s deposit suspension aims to prevent potential losses from double-spending attacks while the network remains compromised.

Other exchanges may implement similar measures until normal mining distribution resumes.

A 51% attack allows attackers to spend the same coins multiple times by reversing confirmed transactions. Exchanges become primary targets in such attacks since they handle large transaction volumes and hold significant cryptocurrency reserves.

The Monero network’s proof-of-work consensus mechanism requires majority hashrate control to validate transactions. Qubic’s dominance theoretically gives it the power to reorganize blocks and censor transactions on the network.