In builtin.c in zsh before 5.4, when sh compatibility mode is used, there is a NULL pointer dereference during processing of the cd command with no argument if HOME is not set.
"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2017-18205.json"
[ { "events": [ { "introduced": "0" }, { "fixed": "5.4" } ] } ]