gzip before 1.3 in Solaris 8, when called with the -f or -force flags, will change the permissions of files that are hard linked to the target files, which allows local users to view or modify these files.
Buffer overflows in gzip 1.3x, 1.2.4, and other versions might allow attackers to execute code via a long file name, possibly remotely if gzip is run on an FTP server.