Blockchain network used by the altcoin called Pigeoncoin was attacked by hackers who stole 235 million PGN tokens, worth about $15 000. The attackers exploited CVE-2018-17144 bug which was recently fixed by the recent Bitcoin Network code update. The said vulnerability makes blockchain vulnerable to a combination of DoS and double- spend attacks.
Despite the comparatively low amount of lost funds, the attack was indeed impressive, as the intruders managed to get their hands on the quarter of all existing Pigeoncoins, while literally devastating its network. The hackers applied 51% attack in combination with double-spend attack.
In late September, Bitcoin developers discovered a critical bug (CVE-2018-17144) which allowed this type of attack. Bitcoin was patched before such an attack could occur. Unfortunately, Pigeoncoin was based on Bitcoin, and its developers did not patch the coin until it was too late.
Being now publicly disclosed, this bug puts other altcoins operated with the use of unupdated Bitcoin code at great risk of repeating the fate of Pigeoncoin.