I have recently read the news about Google Chrome Buffer Overflow vulnerability (see this link). Admittedly, I was ignorant enough not to understand how a buffer overflow can cause severe security breaches! Wikipedia came to the rescue, as well as some research into the topic of Assembly-language programming. At last I can understand how SEVERE such an attack could be!
You can dig for it too ;-)
check the Wikipedia article,
and the excellent book of Programming from the Ground Up, for much better understanding of Assembly: