firehol in firehol 1.256 allows local users to overwrite arbitrary files via a symlink attack on (1) /tmp/.firehol-tmp-#####-*-* and (2) /tmp/firehol.conf temporary files. NOTE: the vendor disputes this vulnerability, stating that an attack "would require an attacker to create 1073741824*PID-RANGE symlinks.
https://bugs.gentoo.org/show_bug.cgi?id=235770
http://www.openwall.com/lists/oss-security/2008/10/30/2