vim (aka gvim) allows local users to modify files being edited by other users via a symlink attack on the backup and swap files, when the victim is editing the file in a world writable directory.
https://exchange.xforce.ibmcloud.com/vulnerabilities/6628
http://www.novell.com/linux/security/advisories/2001_012_vim.html
http://www.calderasystems.com/support/security/advisories/CSSA-2001-014.0.txt