What was the date of the Bitcoin value overflow exploit?

The Bitcoin value overflow exploit occurred on August 15, 2010.

The vulnerability came from an integer overflow in Bitcoin’s transaction validation. Although the software checked that transaction outputs did not exceed the inputs, the total output value could wrap around when it exceeded the limit of a 64-bit integer.

An attacker exploited the flaw by creating a transaction that appeared to spend 0.5 bitcoin while generating more than 184 billion bitcoins—roughly 92 billion for each of two recipient addresses. This was not a normal theft from existing wallets; it was an unintended inflation of the currency supply.

Developers and miners responded quickly by releasing patched software and reorganizing the blockchain to remove the invalid transaction. The incident is often confused with later exchange hacks, but it was a protocol-level bug in Bitcoin’s early code.