Xscreensaver before 4.15 creates temporary files insecurely in (1) driver/passwd-kerberos.c, (2) driver/xscreensaver-getimage-video, (3) driver/xscreensaver.kss.in, and the (4) vidwhacker and (5) webcollage screensavers, which allows local users to overwrite arbitrary files via a symlink attack.
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A10848
https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=182286
https://bugzilla.redhat.com/bugzilla/attachment.cgi?id=124968
http://www.vupen.com/english/advisories/2006/1948
http://www.securityfocus.com/bid/9125
http://www.redhat.com/support/errata/RHSA-2006-0498.html
http://www.novell.com/linux/download/updates/90_i386.html
http://support.avaya.com/elmodocs2/security/ASA-2006-107.htm
http://secunia.com/advisories/20782
http://secunia.com/advisories/20456
http://secunia.com/advisories/20226