Kraken Suspends Monero Deposits After 51% Mining Power Surge

In Summary

  • Kraken halts Monero deposits after Qubic controls 51% of hashrate
  • Six-block reorganization sparks debate over full 51% attack success
  • Event highlights risks of concentrated mining on proof-of-work chains
  • Developers dispute claims; security experts warn potential blockchain censorship


Catenaa, Thursday, August 21, 2025-  Kraken, a major crypto exchange, paused Monero (XMR) deposits after one mining pool reportedly controlled more than half of the network’s hashing power, raising security concerns.

The pool, Qubic, claimed it reorganized six blocks following a month-long effort to dominate the blockchain, potentially allowing coin double-spending and transaction manipulation. Monero developers disputed the severity of the incident, arguing that the reorganization does not prove a full 51% attack.

Monero ranks as the 29th-largest cryptocurrency, valued at about $6 billion, and is widely used for privacy-focused transactions. The recent events began in late June when Qubic redirected its proof-of-work capacity, initially intended for AI applications, toward Monero mining.

After a temporary drop in hashrate caused by a DDoS attack in early August, Qubic regained control and claimed majority dominance.

The incident highlights the vulnerability of proof-of-work blockchains with concentrated mining power, underscoring risks when a single entity approaches or surpasses 50% control.

Security experts remain divided, with some warning the blockchain could be rewritten or censored, while developers maintain that a limited six-block reorganization is not conclusive evidence of a network compromise.

Kraken emphasized the precautionary nature of its deposit suspension and said it is monitoring the network closely.

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