A certain application-launch script in Mozilla Firefox before 3.5.14 and 3.6.x before 3.6.11, Thunderbird before 3.0.9 and 3.1.x before 3.1.5, and SeaMonkey before 2.0.9 on Linux places a zero-length directory name in the LD_LIBRARY_PATH, which allows local users to gain privileges via a Trojan horse shared library in the current working directory.