Subject: [ASA-201804-7] zsh: denial of service

Arch Linux Security Advisory ASA-201804-7
=========================================

Severity: Medium
Date    : 2018-04-19
CVE-ID  : CVE-2018-7548 CVE-2018-7549
Package : zsh
Type    : denial of service
Remote  : No
Link    : https://security.archlinux.org/AVG-642

Summary
=======

The package zsh before version 5.5-1 is vulnerable to denial of
service.

Resolution
==========

Upgrade to 5.5-1.

# pacman -Syu "zsh>=5.5-1"

The problems have been fixed upstream in version 5.5.

Workaround
==========

None.

Description
===========

- CVE-2018-7548 (denial of service)

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

- CVE-2018-7549 (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.

Impact
======

A local attacker can cause a denial of service via a specially input.

References
==========

https://sourceforge.net/p/zsh/code/ci/110b13e1090bc31ac1352b28adc2d02b6d25a102
https://sourceforge.net/p/zsh/code/ci/c2cc8b0fbefc9868fa83537f5b6d90fc1ec438dd
https://security.archlinux.org/CVE-2018-7548
https://security.archlinux.org/CVE-2018-7549