Arch Linux: Arbitrary code execution (CVE-2018-1100)

A stack-based buffer overflow has been found in zsh <= 5.4.2, in the checkmailpath() function, where unchecked strings from the MAILCHECK variable are copied to a buffer. A local, unprivileged user can create a specially crafted message file, which, if used to set a custom "you have new mail" message, leads to code execution in the context of the user who receives the message. If the user affected is privileged, this leads to privilege escalation.