Both ICQ instant messenger for Windows and the ICQ web site contain vulnerabilities that could allow attackers to take control of a user’s ICQ account. ICQ told that it was in the process of developing and testing a security fix for the flaw. Heise Security was able to reproduce the flaw using the current 7.5 version of ICQ. The flaw was discovered by security researcher Levent Kayan. Kayan recently discovered a similar hole in the Skype client that allows attackers to control a Skype account.
Source: https://thehackernews.com/2011/07/icq-vulnerable-to-account-theft-using.html