The Xsession script, as used by X Display Manager (xdm) in NetBSD before 20060212, X.Org before 20060317, and Solaris 8 through 10 before 20061006, allows local users to overwrite arbitrary files, or read another user’s Xsession errors file, via a symlink attack on a /tmp/xses-$USER file.
secunia.com/advisories/22992
securitytracker.com/id?1017015
sunsolve.sun.com/search/document.do?assetkey=1-26-102652-1
support.avaya.com/elmodocs2/security/ASA-2006-250.htm
www.netbsd.org/cgi-bin/query-pr-single.pl?number=32805
bugs.freedesktop.org/show_bug.cgi?id=5898
exchange.xforce.ibmcloud.com/vulnerabilities/29427
oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A2205