Despite only suffering an 18- Block reorg attack that reversed around 117 transactions, the price of Monero (XMR) still unexpectedly jumped more than 7%.
Monero (XMR) Price Surges 7% Despite Qubic Attack, Reversing Over 117 Transactions
On September 14, 2025, the anonymity-oriented coinMonero (XMR) was attacked by the Qubic project, causing 18 Block to be reorged and 117 previously confirmed transactions to be reversed, raising many concerns about the security of the Monero blockchain.
Monero (XMR) suffered an 18- Block reorganization, as reported by @OrangeFren . Users accepting XMR payments are advised to wait longer than the usual 10 confirmations. SlowMist's @evilcos warned that ignoring reorg risks could expose the community to potential double-spending…
— Wu Blockchain (@WuBlockchain) September 14, 2025
Overview of the attack
- The reorg attack occurred at 5:12 AM UTC on September 14, starting at Block 3499659 and lasting for 43 minutes. By Block 3499676, the newly created chain had completely replaced the previous 18 Block .
- The incident resulted in the reversal of around 117 previously confirmed transactions, raising serious concerns about the integrity of the Monero blockchain.
- This is also a reorg that far exceeds Monero 's 10- Block lock protection mechanism , which is designed to prevent reorgs deeper than 10 Block. However, the attack lasted 18 Block, completely breaking this defense.
- Behind the attack was Qubic , a Mining project that uses the Useful Proof-of-Work (uPoW) mechanism, paying generous rewards to Monero Miners to participate in the project's economy.
- Qubic currently has more than 51% of Monero's hashrate, meaning it has more computing power than the rest of the network. With this ratio, Qubic is fully capable of conducting a 51% Attack, allowing it to replace valid Block with other Block .
- Notably, this is not the first time Monero has been targeted by Qubic. The project conducted a smaller reorg of six Block in August 2025, but the September 14 incident is XEM the most serious in Monero 's history in terms of both scale and severity.
Reactions from experts
- “In the last 1,440 Monero Block , Qubic has mined 333 Block (about 23% of the total). However, of the Block mined by the entire network, 473 Block were Orphan (i.e. discarded, not included in the main chain ), with Qubic alone accounting for 140 of Block (equivalent to 29.6%). This brings the overall Orphan rate to 43.34%, bringing Qubic’s mining efficiency down to 86.19%,” said Monero developer sech1.
- In other words, even though Qubic has overwhelming computing power and performs many reorgs, because of their “selfish mining” strategy (only publishing beneficial Block ), they still lose XMR instead of earning more. In essence, this is more of an expensive PR stunt than an XMR mining strategy.
- KOL Vini Barbosa (@vinibarbosabr) said that some community members have announced that they will stop accepting XMR payments until the issue is completely resolved. They called on Monero developers to quickly find a solution, and recommended that those who still want to use XMR set a minimum confirmation time of 20 Block to minimize risks.
- SlowMist founder Yu Xian ( @evilcos ) believes that if the Monero community doesn’t take the Block reorganization issue seriously, the network will always be in a dangerous state. This doesn’t mean that a double-spend attack will definitely occur on the network, but the mere possibility of doing so is a major threat.
Solutions considered
- Researcher Rucknium believes that Monero nodes will likely have to temporarily implement DNS checkpoints, where nodes will only fetch Block data from trusted DNS servers.
- This may help prevent repeated reorgs, but it also takes away some of the decentralization that is at the core of Monero. However, Monero has Capital lost some of its decentralization with Qubic controlling over 51% of the network's hashrate.
- The Monero community has previously discussed several approaches to preventing 51% Attack, including:
- Localize mining hardware , reduce dependence on large mining pools.
- Apply merge mining , allowing XMR to be mined in parallel with Bitcoin and some other coins.
- Implement ChainLocks similar to Dash for increased protection against reorgs.
- However, no solution has been effectively implemented so far, and Qubic still holds the majority of control over the network.
XMR Price Surges After Attack
- Surprisingly, the price of XMR remained almost flat during the reorg. The Token even jumped from $287 to over $308, recording a 5.9% increase in the past 24 hours.
XMR price movement in the last 24 hours, screenshot on CoinGecko at 11:00 AM on 09/15/2025
Crypto podcast host @xenumonero suggests that Qubic may have intentionally “supported” XMR to maintain its position and avoid losing trust from the community.
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