Monero pumps 7% despite an 18-block reorg prompting concerns

Monero’s privacy token rose more than 7% despite its blockchain suffering an 18-block reorg that reversed around 117 transactions and triggered community concerns over the Monero ecosystem’s future.

The security breach was committed by the team behind Qubic, a layer 1 AI-focused blockchain and mining pool that amassed 51% hashrate on Monero and committed a six-block reorg last month.

The reorg started at block 3499659 on Sunday at 5:12 am UTC and finished at block 3499676 roughly 43 minutes later, according^[1] to sources who run Monero nodes and shared their command-line consoles on X. 

Monero’s latest security breach was also confirmed^[2] by cryptocurrency protocol researcher Rucknium on GitHub.

Surprisingly, the Monero (XMR^[3]) token traded relatively flat while the reorg was happening, and a little over eight hours later, it went on a 7.4% rally from $287.54 to $308.55, CoinGecko data^[4] shows. XMR managed to rise despite the broader market dropping around 1% on Sunday.

Crypto podcaster xenu — one of the first to report Monero’s reorg — suggested^[5] Qubic may have been trying to implement mechanisms to “stop the bleeding” of XMR’s price.

The reorg — claimed^[7] by xenu as the largest in the network’s history — has prompted discussion over how to handle the privacy-chain moving forward.

The repeated attacks highlight how proof-of-work blockchains can be tampered with when they’re not sufficiently decentralized, hindering their use as a monetary network.

“Personally, I don’t consider the Monero network reliable at this point. I’ll stop accepting XMR for payments until this situation is resolved,” one crypto pundit, Vini Barbosa, said^[8] on Sunday on X.

Monero may need to centralize to curb Qubic’s influence

Rucknium said it is “highly likely” that Monero node operators will start temporarily adopting Domain Name System (DNS) checkpoints — where nodes fetch trusted block data from community DNS servers — as a solution to preventing the repeated reorgs.

However, that comes at a cost to centralization,^[9] which some would argue has already been tarnished by Qubic’s more than 51% hash rate^[10] share.

This is what looks like the 19 reorganization blocks in my monerod $XMR pic.twitter.com/30awmyqgCb^[11][12]

— Ʊɬɱʘ 🏴 a³ ɱ ᕮ 𐤊 ױ א ⛛ (@Ulmonan0) September 14, 2025^[13]

“If no one in the Monero community takes the issue of block reorganization seriously, then this Sword of Damocles will always hang over Monero’s head,” Yu Xian, founder of blockchain security compay, SlowMist, posted^[14] to X.

Monero has considered solutions to prevent 51% attacks 

Previously, the Monero community explored a potential overhaul of its proof-of-work consensus mechanism to make the network resistant to 51% attacks.^[15][16]

Among those proposals included localizing mining hardware^[17], switching to a merge mining algorithm, allowing XMR to be mined with Bitcoin (BTC^[18]) and other cryptocurrencies, and adopting Dash’s ChainLocks solution.

To date, no solution has been effectively implemented, and Qubic still has significant influence over the privacy-focused network.

Related: Kraken pauses Monero deposits following 51% attack^[19]

Monero had a 10-block lock mechanism to protect transactions from reorgs up to 10 blocks, but the recent 18-block reorg exceeded that safeguard, Rucknium noted.

Despite the network breaches, XMR has held relatively strong since reports were first made of Qubic’s takeover around July 28 — falling only 5.85%.

Magazine: 3 people who unexpectedly became crypto millionaires… and one who didn’t^[20]