envvars (aka envvars-std) in the Apache HTTP Server before 2.4.2 places a zero-length directory name in the LD_LIBRARY_PATH, which allows local users to gain privileges via a Trojan horse DSO in the current working directory during execution of apachectl.
Ubuntu-Description
jdstrand> Debian/Ubuntu packages contain 038_no_LD_LIBRARY_PATH (see http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=276670 for more information)