What made this a very dangerous security flaw is that Skype stores full conversation histories in the cloud, meaning someone that hijacks your account can look through your personal conversations.
Details on how the attack worked can be read at The Next Web, the issue was first posted on a Russian forum in September.
We reproduced the attack, step-by-step, and managed to access the Skype accounts of TNW writer (with permission) Josh Ong (as well as editor Matt Brian to verify again) with only their email addresses. Essentially, that email address is used to create a new account with your own email address tied to it. Then, minus a couple of key steps, you can use a password reset token to gain access to your target’s account.