From $URL: There's a potential buffer overflow in utils.c:checkmailpath() function where unchecked strings from the MAILCHECK variable are copied to a buffer. This bug corresponds to CVE-2018-1100 and credit to Richard Maciel Costa for finding it. Reference: https://sourceforge.net/p/zsh/code/ci/31f72205630687c1cef89347863aab355296a27f/
This issue was resolved and addressed in GLSA 201805-10 at https://security.gentoo.org/glsa/201805-10 by GLSA coordinator Christopher Diaz Riveros (chrisadr).