Monero over spending risk

In this post:

• Monero (XMR) has suffered an 18-block blockchain reorganization, raising fears of double-spend attacks.
• Users, merchants, and exchanges are being urged to wait for more than the usual 10 confirmations before accepting XMR.

The incident follows earlier warnings about hash power concentration and security risks in the networkMonero (XMR) users have been put on high alert after the network experienced a rare and unusually deep 18-block chain reorganization. The event, confirmed by monitoring screenshots shared on X, has raised widespread concern that the crypto’s network is now vulnerable to double-spending attacks.

A blockchain reorganization happens when competing versions of the chain are produced, and one overtakes the other. The “losing” chain’s blocks along with all the transactions inside them, will be discarded as a result. 

In Monero’s case, new blocks are created roughly every two minutes. An 18-block reorganization effectively rewrites more than half an hour of transaction history.

While minor reorganization of one or two blocks can occur naturally in proof-of-work systems, an 18-block reorganization is highly unusual and suggests deliberate manipulation or an abnormal concentration of mining power.

A security researcher and founder of SlowMist Cosine warned, “If the Monero community does not take block reorganizations seriously, this sword of Damocles will always hang over Monero’s head. It may not always result in a double-spend, but the ability to do so now exists — even without strictly controlling 51% of the network hash rate.”