Monero Releases ‘Fluorine Fermi’ Update to Boost Protection Against Spy Nodes

Privacy-focused blockchain Monero (XMR) has rolled out a major software update aimed at strengthening defenses against so-called “spy nodes,” malicious actors attempting to compromise user ￰0￱ Takeaways: Monero released its “Fluorine Fermi” update (v0.18.4.3) to improve protection against spy nodes that threaten user ￰1￱ upgrade introduces a smarter peer selection algorithm to avoid connections with potentially malicious subnet ￰2￱ update reinforces Monero’s ongoing battle to preserve transaction anonymity amid growing surveillance ￰3￱ new release, named “Fluorine Fermi” (v0.18.4.3), was announced Thursday on X , with the Monero team calling it “a highly recommended update” for all ￰4￱ upgrade introduces a smarter peer selection algorithm designed to help nodes avoid large subnet groups commonly associated with surveillance activity, pushing users to connect with safer peers ￰5￱ Strengthens Network Privacy With New Defense Against Spy Nodes Spy nodes are a long-standing concern in Monero’s ￰6￱ are malicious nodes or networks that attempt to link IP addresses with transactions, effectively undermining the privacy guarantees of the blockchain.

Monero’s latest update adds another layer of protection to counter such threats, while also improving network reliability and ￰7￱ Monero community has long viewed these attacks as one of the most persistent threats to its mission of untraceable ￰8￱ response, developers and researchers have explored multiple strategies, including running self-operated nodes, ban lists for suspicious IPs, and the Dandelion++ protocol, which obscures the origin of transactions before they spread through the ￰9￱ late 2024, the Monero Research Lab proposed a mechanism allowing node operators to block known spy IPs. We're excited to announce that CLI v0.18.4.3 'Fluorine Fermi' has been released!

'This is a highly recommended release that enhances protection against spy nodes.' — Monero (XMR) (@monero) October 9, 2025 However, experts noted that determined adversaries could simply create new nodes, making this a temporary fix rather than a long-term ￰10￱ over Monero’s network security were reignited last year after a leaked Chainalysis video claimed the analytics firm had traced transactions dating back to 2021 using its own “malicious nodes.” With Fluorine Fermi, Monero continues its push to stay ahead in what its developers describe as an ongoing “cat-and-mouse game” between privacy advocates and surveillance entities, a defining battle for the future of anonymous blockchain ￰11￱ Claims 51% Control of Monero Hashrate After Recovering From DDoS Attack In August, Layer-1 blockchain Qubic claimed it seized 51% of Monero’s hashrate , a level of control that in theory could rewrite the chain, double-spend transactions, or censor activity, all for an estimated cost of just $100,000 per ￰12￱ pool initially struggled, falling back to seventh-largest on the network after a distributed denial of service (DDoS) attack on August 4 reduced its hashrate from 2.6 gigahashes per second (GH/s) to just 0.8 GH/s.

However, Qubic later restored its power and claimed majority control. A 51% attack occurs when one party controls the majority of a blockchain’s mining power or stake, allowing them to alter the chain’s history or block ￰13￱ founder Sergey Ivancheglo admitted the strategy was designed to monopolize Monero’s mining, eventually rejecting blocks from rival pools.