> For the complete documentation index, see [llms.txt](https://docs.metaverse-ico.net/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.metaverse-ico.net/whitepaper/attack-vectors-and-security/double-spending.md).

# Double Spending

Double-spending is a type of attack where the attacker makes the same transaction operation to be performed more than once.

The attacker aims to make multiple expenses by sending the same signed transaction back to the network while the transaction is still in the process of being recorded in blocks.

The same transaction sent more than once by the attacker is subjected to the "Pre-verified Sign Is Valid" stage by MetaAnthill. Unsigned transactions are denied directly, and nodes are prevented from performing the same transaction a second time.

![](https://docs.metatime.com/whitepaper/~gitbook/image?url=https%3A%2F%2F989455816-files.gitbook.io%2F%7E%2Ffiles%2Fv0%2Fb%2Fgitbook-x-prod.appspot.com%2Fo%2Fspaces%252FAIzmobbGXH6E0WrRNrgp%252Fuploads%252FXSUgSY0UYRxq7DwslPxP%252Fdoublespending.png%3Falt%3Dmedia%26token%3D454e4b14-311d-4995-ba38-a6ad2172aaf0\&width=768\&dpr=3\&quality=100\&sign=7947b4823433f784168eaa6955c206ff\&sv=3)

![](https://docs.metatime.com/whitepaper/~gitbook/image?url=https%3A%2F%2F989455816-files.gitbook.io%2F%7E%2Ffiles%2Fv0%2Fb%2Fgitbook-x-prod.appspot.com%2Fo%2Fspaces%252FAIzmobbGXH6E0WrRNrgp%252Fuploads%252FMg1g858DaJejqd7wnqcY%252Fdipnot.png%3Falt%3Dmedia%26token%3D17ebe656-6885-4b97-a74f-d79a5ec9f3f8\&width=768\&dpr=3\&quality=100\&sign=aa4de4fe235f4038de396689fd2abc1b\&sv=3)


---

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