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.
Kernel logging daemon (klogd) in Linux does not properly cleanse user-injected format strings, which allows local users to gain root privileges by triggering malformed kernel messages.