Amazon Linux 2 : zsh (ALAS-2018-986)

critical Nessus Plugin ID 109139


The remote Amazon Linux 2 host is missing a security update.


NULL dereference in cd in sh compatibility mode under given circumstances

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. (CVE-2017-18205)

NULL pointer deref when using ${(PA)...} on an empty array result :

In subst.c in zsh through 5.4.2, there is a NULL pointer dereference when using ${(PA)...} on an empty array result. (CVE-2018-7548)

Buffer overrun in xsymlinks

In utils.c in zsh before 5.4, symlink expansion had a buffer overflow.

Crash on copying empty hash table

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. (CVE-2018-7549)


Run 'yum update zsh' to update your system.

See Also

Plugin Details

Severity: Critical

ID: 109139

File Name: al2_ALAS-2018-986.nasl

Version: 1.1

Type: local

Agent: unix

Published: 4/18/2018

Updated: 4/18/2018

Supported Sensors: Frictionless Assessment Agent, Frictionless Assessment AWS, Nessus Agent

Risk Information


Risk Factor: Medium

Score: 5.9


Risk Factor: High

Base Score: 7.5

Vector: AV:N/AC:L/Au:N/C:P/I:P/A:P


Risk Factor: Critical

Base Score: 9.8

Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Vulnerability Information

CPE: p-cpe:/a:amazon:linux:zsh, p-cpe:/a:amazon:linux:zsh-debuginfo, p-cpe:/a:amazon:linux:zsh-html, cpe:/o:amazon:linux:2

Required KB Items: Host/local_checks_enabled, Host/AmazonLinux/release, Host/AmazonLinux/rpm-list

Patch Publication Date: 4/5/2018

Reference Information

CVE: CVE-2017-18205, CVE-2017-18206, CVE-2018-7548, CVE-2018-7549

ALAS: 2018-986