If you are using Winamp version 2.79 or earlier you should upgrade now.
This is from online.securityfocus.com: (<- read more here)

"A mp3 file can contain the ID3v2 tag. It's a newer version of the ID3v1
tag and carries information like title, artist and album. The tag is
parsed by Winamp when a mp3 file is loaded.

If the minibrowser is enabled, Winamp will try to query a script on
http://info.winamp.com for extra information about the song, based on data
from the ID3v2 tag. The buffer overflow condition occours when the url
string intended to be sent to the minibrowser is created. That means the
buffer overflow occours before any actual internet connection to
info.winamp.com is being made."