Kraken Halts Monero Deposits After Qubic’s 51% Control

Kraken Freezes Monero Deposits After Qubic Claims 51% Control

Written by Aaron S.,

Editor-In-Chief

Last Updated: August 18, 2025

Key Takeaways

Kraken paused Monero deposits after one pool claimed over 51% of the network’s mining power, which raised risks to blockchain security;
Qubic said it reorganized six Monero blocks, but its hashrate later dropped after a DDoS attack before regaining majority control;
A 51% attack lets a miner change transactions or double-spend, which threatens trust until the hashrate is spread more evenly again.

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Kraken $560.08M has stopped accepting Monero XMR $268.81 deposits after one mining pool appeared to control more than half of the network’s computing power.

The crypto exchange explained on August 15, "As a security precaution, we have paused Monero deposits after detecting that a single mining pool has gained more than 50% of the network’s total hashing power. This concentration of mining power poses a potential risk to network integrity".

Qubic, a project focused on AI and blockchain, stated on August 11 that it had reached a majority share of Monero’s hashrate. The group also said it had changed six blocks on the chain, though members of the Monero community questioned whether this counted as an actual attack.

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At one point, however, the pool slipped to the seventh-largest miner. On August 4, Qubic suffered a denial-of-service attack (DDoS), where servers are overloaded with fake traffic so real connections cannot get through.

This caused its hashrate to drop from 2.6 gigahashes per second to 0.8 GH/s, according to Sergey Ivancheglo, who said he was behind the 51% attack.

Despite these issues, Qubic’s pool regained strength and eventually controlled most of the Monero network’s computing power once again.

A 51% attack is a situation where one miner or pool has enough power to change recent transactions or even spend the same coins more than once. This undermines trust in the blockchain until control shifts back to a more balanced state.

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