Quote from: shorena on October 04, 2015, 04:20:24 PM

Quote from: DarkRavenGamer on October 04, 2015, 04:09:19 PM

Something very strange happened today. blockchain.info let me send 1.48 BTC when I only had 0.6. I had a incoming transaction of 1 BTC. For some reason it made the sending transaction twice (received and sent BTC in the same block) and it is displayed as unconfirmed and my balance is negative.

screenshot: https://i.gyazo.com/ea177ad2f4f3bd0ef39bb2be6500712a.png

Can I remove the unconfirmed transaction? Why did it send twice?

It did not send it twice, but the transaction you send (A) was modified along the way by a node. This create transaction B that spends the same coins and sends them to the same address as A, but has a different transaction ID. This is called a "malleabiltiy attack" and can be fixed by contacting blockchain.infos support. Only A or B can confirm never both.

More here -> https://bitcointalk.org/index.php?topic=1198032.0

I see. So there is someone doing this on purpose? For what reason?