In utils.c in zsh before 5.0.6, there is a buffer overflow when scanning very long directory paths for symbolic links.
https://usn.ubuntu.com/3593-1/
https://sourceforge.net/p/zsh/code/ci/3e06aeabd8a9e8384ebaa8b08996cd1f64737210
https://euvd.enisa.europa.eu/vulnerability/EUVD-2014-1139