Monero’s privateness chain endured its deepest-ever chain reorganization within the final 24 hours, when 18 consecutive blocks had been changed, briefly “rewriting” roughly 36 minutes of ledger historical past and invalidating about 118 already-confirmed transactions. A number of unbiased displays flagged the occasion late Sunday into Monday, describing a rollback spanning block heights 3,499,659 by way of 3,499,676 earlier than nodes converged on a brand new greatest chain. With Monero focusing on two-minute blocks, an 18-block reorg interprets to ~36 minutes of historical past—a rare depth for a mature proof-of-work community.
Monero Hit By Report 18 Block Reorg
“The assault in opposition to Monero is again. Hours in the past XMR skilled an 18-block reorg. In the event you settle for XMR be certain that to attend for greater than the standard 10 confs,” warned unbiased monitor OrangeFren as alerts circulated throughout crypto social channels. The put up, amplified by a number of trade accounts, captured the speedy operational takeaway for retailers and providers: elevate affirmation thresholds till circumstances normalize.
The incident comes a month after the controversial AI-oriented mission Qubic claimed to have marshaled a majority of Monero’s hashrate, a marketing campaign that coincided with a six-block reorg in August and led to short-term deposit suspensions at some exchanges. Safety researchers on the time cautioned that the August occasion didn’t, by itself, show sustained 51% dominance—streaks of mining “luck” can produce quick, probabilistic reorganizations—however additionally they warned that persistent hashrate focus raises the ceiling on how deep such reorgs can go. Monday’s 18-block episode materially raises that ceiling.
Neighborhood voices reacted with a mixture of alarm and realism. SlowMist founder Yu Xian commented through X: “If nobody within the Monero group takes the problem of block reorganization severely, then this Sword of Damocles will all the time hold over Monero’s head… It might not essentially perform a double-spend assault, however having this functionality… It doesn’t even should strictly exceed 51% of the hash energy…”
Qubic founder Sergey Ivancheglo, who is thought by the alias “Come-from-Past”, posted through X: “Monero will keep as a result of Qubic wished it to remain.”
#Monero will keep as a result of #Qubic wished it to remain.https://t.co/49MZzF5WaI pic.twitter.com/qd7wPVoDOu
— Come-from-Past (@c___f___b) September 14, 2025
At a technical degree, a sequence reorg happens when two legitimate histories compete and the community in the end converges on the one with probably the most gathered proof-of-work, discarding the opposite and any transactions unique to it. In Monero’s design, two-minute goal block intervals and dynamic block sizing purpose to maintain throughput easy whereas preserving privateness primitives like ring signatures and stealth addresses.
In follow, nevertheless, a miner or pool with outsized hashpower can—a minimum of in bursts—privately lengthen a aspect chain after which launch it, “out-working” the general public tip and forcing nodes to reorganize. That’s what seems to have occurred right here, with a depth that exceeded the de facto 10-confirmation consolation zone generally utilized by wallets and exchanges.
The August–September sequence has re-opened a contentious debate inside Monero about defenses. Proposals span the spectrum: “rolling 10-block checkpoints” that finalize latest blocks to cap reorg depth; adopting components akin to Sprint’s ChainLocks to bolt on a finality layer; “detective mining” incentives to counter selfish-mining methods on the pool degree; and even merge-mining ideas that may piggyback Monero’s safety on a bigger PoW base.
Every trade-off is sharp: checkpoints and ChainLocks introduce levels of centralization or new belief assumptions, whereas pool-level adjustments could also be erratically adopted. The group has not but coalesced round a particular repair, however the urgency has unmistakably elevated.
Markets handled the occasion with stunning resilience. Inside hours, XMR rallied between roughly 5% and seven%, buying and selling above $300 on some venues.
Featured picture created with DALL.E, chart from TradingView.com
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