Multiple shell programs on various Unix systems, including (1) tcsh, (2) csh, (3) sh, and (4) bash, follow symlinks when processing << redirects (aka here-documents or in-here documents), which allows local users to overwrite files of other users via a symlink attack.
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A4047
http://www.securityfocus.com/bid/1926
http://www.securityfocus.com/archive/1/146657
http://www.redhat.com/support/errata/RHSA-2000-121.html
http://www.redhat.com/support/errata/RHSA-2000-117.html
http://www.linux-mandrake.com/en/security/MDKSA-2000-075.php3
http://www.linux-mandrake.com/en/security/MDKSA-2000-069.php3
http://www.kb.cert.org/vuls/id/10277
http://www.debian.org/security/2000/20001111a
http://www.calderasystems.com/support/security/advisories/CSSA-2000-043.0.txt
http://www.calderasystems.com/support/security/advisories/CSSA-2000-042.0.txt
http://marc.info/?l=bugtraq&m=97561816504170&w=2
http://distro.conectiva.com.br/atualizacoes/?id=a&anuncio=000354
http://distro.conectiva.com.br/atualizacoes/?id=a&anuncio=000350
http://archives.neohapsis.com/archives/tru64/2002-q1/0009.html
http://archives.neohapsis.com/archives/bugtraq/2000-10/0418.html