Double Spend
An attack where the same funds are spent twice by exploiting a chain reorg or fork.
An attack where the same funds are spent twice by exploiting a chain reorg or fork.
entity.trust_high
Sep 2026 · Verheidsscore: 50%
What is Double Spend?
An attack where the same funds are spent twice by exploiting a chain reorg or fork.
- Category
- concept
- Type
- Authority Node
- Sources
- 1
In a double-spend, an attacker broadcasts a payment, waits for it to be accepted, then mines or orchestrates a competing chain (or uses a network race) that excludes the first payment while spending the same coins elsewhere. Proof-of-work m
Double-spending would destroy a currency's value — it is why consensus design matters. Confirmations exist to make double-spends economically infeasible, and finality (in PoS) eliminates them after settlement. Understanding double-spend ris
Knowledge Graph
11 relationsRelated
1. What Is a Double-Spend
A double-spend is an attack in which the same digital token is spent more than once, by exploiting a race or a chain reorg. It is the fundamental problem that blockchain consensus solves.
2. How It Works
In a double-spend, an attacker broadcasts a payment, waits for it to be accepted, then mines or orchestrates a competing chain (or uses a network race) that excludes the first payment while spending the same coins elsewhere. Proof-of-work makes this costly: the attacker must outpace the honest chain. Proof-of-stake finality prevents reorgs after finalization.
3. Why It Matters
Double-spending would destroy a currency's value — it is why consensus design matters. Confirmations exist to make double-spends economically infeasible, and finality (in PoS) eliminates them after settlement. Understanding double-spend risk explains why merchants wait for confirmations and why fast finality is valued.
4. Key Facts
- 51% attacks enable double-spends on vulnerable networks
- Reorg attacks are the main vector on PoW chains
- Finality gadgets (Casper, Tendermint) settle transactions irreversibly
- Small-cap coins are far more susceptible than Bitcoin or Ethereum
5. Related Concepts
- consensus
- block-confirmation
- reorg
- proof-of-work
Frequently Asked Questions
What is Double Spend?
An attack where the same funds are spent twice by exploiting a chain reorg or fork.
How does Double Spend work?
A double-spend is an attack in which the same digital token is spent more than once, by exploiting a race or a chain reorg. It is the fundamental problem that blockchain consensus solves. In a double-spend, an attacker broadcasts a payment, waits for it to be accepted, then mines or orchestrates a
Why does Double Spend matter in Web3?
- block-confirmation - reorg - proof-of-work