unzip -- permission race vulnerability

Imran Ghory reports a vulnerability within unzip. The
vulnerability is caused by a race condition between
extracting an archive and changing the permissions of the
extracted files. This would give an attacker enough time to
remove a file and hardlink it to another file owned by the
user running unzip. When unzip changes the permissions of
the file it could give the attacker access to files that
normally would not have been accessible for others.