vi as included with SCO OpenServer 5.0 - 5.0.6 allows a local attacker to overwrite arbitrary files via a symlink attack.
https://exchange.xforce.ibmcloud.com/vulnerabilities/6588
https://euvd.enisa.europa.eu/vulnerability/EUVD-2001-0618
http://www.securityfocus.com/bid/2752
http://www.kb.cert.org/vuls/id/747736
http://archives.neohapsis.com/archives/bugtraq/2001-05/0220.html