Monero undergoes 18-block reorganization and tension with Qubic returns

• Monero undergoes reorganization of 18 blocks and 118 transactions
• Community once again questions Qubic's role in the network
• XMR appreciates over 6% after onchain incident

Monero (XMR) experienced an 18-block reorganization, an unusual event that resulted in the invalidation of approximately 117 to 118 transactions over the course of nearly 40 minutes. The episode prompted developers and users to recommend additional caution, suggesting that payments should only be considered final after more than 10 confirmations—a traditional network standard.

Reorganizations occur when competing versions of a proof-of-work blockchain are mined simultaneously. By adopting the longer, more difficult chain, the network discards blocks from the other version and all transactions contained within them. While recognized as an operational risk in PoW networks, they rarely occur on this scale in Monero.

The Monero Research Lab reported that the alt-chain began at height 3.499.659, leaving dozens of orphaned transactions. Because the event surpassed the nine-block limit, the 10-confirmation block wasn't enough to protect all reverted transactions. Therefore, the group suggested temporarily implementing DNS checkpoints as a way to bolster security.

SlowMist co-founder Yu Xian warned that such reorganizations could open the door to double-spending, even without a single miner holding an absolute majority of the hash power. This risk has reignited debates about Monero's vulnerability and its exposure to large mining pools.

Recently, an 18-block re-org occurred on Monero's mainnet. You can check this by inputting alt_chain_info into your monerod console if your node was operating during the re-org:

18 blocks long, from height 3499659 (437 deep), diff 510191663980291508:…

— Monero Research Lab (Unofficial) (@MoneroResearchL) September 14, 2025

In the community, many again pointed to tensions with Qubic, Sergey Ivancheglo's project. Reports suggest that the pool has stopped reporting its hash rate on public platforms, raising suspicions that it may have been involved in the incident. Podcaster Xenu, well-known within the Monero ecosystem, stated, "This is the biggest reorganization in Monero history," insinuating that Qubic may have resorted to so-called selfish mining.

Article Article 51% 算力…

— Cos(余弦)😶‍🌫️ (@evilcos) September 14, 2025

Ivancheglo, Qubic's founder, refuted the accusations, stating that Xenu "put it all out of his head." Still, the controversy reinforced long-standing discussions about Qubic's dominance of the network, especially after allegations that the project had concentrated up to 51% of the hash rate.

“Analyst” was used in Because @xenumonero pulled all that out of his ass. #Monero #Quic pic.twitter.com/0dXVu5of3J

— Come-from-Beyond (@c___f___b) September 14, 2025

Interestingly, the immediate impact on the market was positive. XMR rose more than 6% in the last 24 hours, while the QUBIC token remained stable, even amid speculation.