The community reorganized 18 blocks and invalidated 118 transfers in its deepest rollback but.
Observers linked the occasion to Qubic’s withheld mining and potential majority hash management.
The incident follows Qubic’s makes an attempt final month to do a 51% assault on the community.
Monero has shrugged off its greatest chain rollback in its 12-year historical past.
The community reorganized 18 blocks, erasing 36 minutes of transaction historical past and invalidating 118 transfers, in accordance with impartial displays disclosing the incident Saturday.
The native token belonging to the Monero blockchain, XMR, has been little impacted, with it rising greater than 5% on the day. It’s up practically 12% on the week to $302.54, CoinGecko knowledge reveals.
Just lately, an 18-block re-org occurred on Monero’s mainnet. You’ll be able to examine this by inputting alt_chain_info into your monerod console in case your node was working throughout the re-org:
18 blocks lengthy, from peak 3499659 (437 deep), diff 510191663980291508:…
— Monero Analysis Lab (Unofficial) (@MoneroResearchL) September 14, 2025
“That is the most important reorg Monero has ever seen,” an XMR neighborhood podcaster generally known as Xenu wrote on X, including that the occasion shattered the previous rule of thumb that ten confirmations have been sufficient to contemplate a transaction closing.
The rollback occurred between September 14 and 15 at block peak 3,499,659, when mining pool Qubic launched a hidden chain that overtook the principle community. Xenu later claimed that Qubic had mined in isolation “due to egocentric mining, even in spite of everything their reorgs.”
Representatives for Monero’s open-sourcing venture and Qubic didn’t instantly return Decrypt’s request for remark.
Egocentric mining is when a miner withholds blocks they discover and later publishes an extended chain that rewrites latest transactions. The tactic takes benefit of proof-of-work guidelines that reward cumulative work with out distinguishing between regular contributions and privately hoarded blocks.
Beneath Monero’s proof-of-work guidelines, the longest legitimate chain is taken into account the “actual” historical past, so nodes instantly change over.
Within the newest case, Qubic’s withheld chain grew longer than the general public one. When it was launched, nodes robotically accepted it because the legitimate historical past, forcing the community to discard the earlier 18 blocks and the 118 transactions they contained.
The transfer successfully erased greater than half an hour of Monero’s latest exercise, although different miners had already confirmed these funds. The reorg additionally demonstrated that ten confirmations didn’t present satisfactory assurance, main exchanges to increase their necessities.
Final month, Qubic trieda 51% assault on Monero because it developed methods to “experiment” and “assist” guard the community in opposition to future assaults.
A 51% assault occurs when somebody controls greater than half of a blockchain’s pc energy and may change how new transactions are recorded, block or reverse them, and doubtlessly spend cash twice (double-spend).
Whereas that try was questioned, some neighborhood estimates on the time urged it might have briefly reached majority management.
Funds as soon as thought of closing have been erased, pointing to how concentrated mining energy threatens the community. Some customers mentioned they would cease accepting Monero till stability returns, whereas others urged miners to maneuver to smaller swimming pools.
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