Back in 2010, there was a transaction that created 184 billion new bitcoins. This was due to the fact that in C++, the amount field is a signed integer and not an unsigned integer. That is, the value could be negative!
The clever transaction passed all the checks, including the one for not creating new bitcoins, but only because the output amounts overflowed past the maximum number. 264 is ~1.84 × 1019 satoshis, which is 184 billion bitcoins. The fee was negative by enough that the C++ code was tricked into believing that the fee was actually positive by 0.1 BTC!
The vulnerability is detailed in CVE-2010-5139 and was patched via a soft fork in Bitcoin Core 0.3.11. The transaction and the extra bitcoins it created were invalidated retroactively by a block reorganization, which is another way of saying that the block including the value overflow transaction and all the blocks built on top of it were replaced.
Back in 2010, there was a transaction that created 184 billion new bitcoins. This was due to the fact that in C++, the amount field is a signed integer and not an unsigned integer. That is, the value could be negative!
The clever transaction passed all the checks, including the one for not creating new bitcoins, but only because the output amounts overflowed past the maximum number. 264 is ~1.84 × 1019 satoshis, which is 184 billion bitcoins. The fee was negative by enough that the C++ code was tricked into believing that the fee was actually positive by 0.1 BTC!
The vulnerability is detailed in CVE-2010-5139 and was patched via a soft fork in Bitcoin Core 0.3.11. The transaction and the extra bitcoins it created were invalidated retroactively by a block reorganization, which is another way of saying that the block including the value overflow transaction and all the blocks built on top of it were replaced.