In zsh before 5.8.1, an attacker can achieve code execution if they control a command output inside the prompt, as demonstrated by a %F argument. This occurs because of recursive PROMPT_SUBST expansion.

In Zsh before 5.8, attackers able to execute commands can regain privileges dropped by the --no-PRIVILEGED option. Zsh fails to overwrite the saved uid, so the original privileges can be restored by executing MODULE_PATH=/dir/with/module zmodload with a module that calls setuid().

An issue was discovered in zsh before 5.6. Shebang lines exceeding 64 characters were truncated, potentially leading to an execve call to a program name that is a substring of the intended one.

An issue was discovered in zsh before 5.6. The beginning of a #! script file was mishandled, potentially leading to an execve call to a program named on the second line.

zsh through version 5.4.2 is vulnerable to a stack-based buffer overflow in the utils.c:checkmailpath function. A local attacker could exploit this to execute arbitrary code in the context of another user.

zsh through version 5.4.2 is vulnerable to a stack-based buffer overflow in the exec.c:hashcmd() function. A local attacker could exploit this to cause a denial of service.

In params.c in zsh through 5.4.2, there is a crash during a copy of an empty hash table, as demonstrated by typeset -p.

In subst.c in zsh through 5.4.2, there is a NULL pointer dereference when using ${(PA)...} on an empty array result.