GDM before 2.4.1.6, when using the "examine session errors" feature, allows local users to read arbitrary files via a symlink attack on the ~/.xsession-errors file.
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A112
http://www.redhat.com/support/errata/RHSA-2003-258.html
http://marc.info/?l=bugtraq&m=106194792924122&w=2
http://mail.gnome.org/archives/gnome-hackers/2003-August/msg00045.html
http://distro.conectiva.com.br/atualizacoes/?id=a&anuncio=000729