A Zsh security update has been released for Ubuntu Linux 18.04 LTS, 20.04 LTS, and 21.10.

USN-5325-1: Zsh vulnerabilities

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Ubuntu Security Notice USN-5325-1
March 14, 2022

zsh vulnerabilities
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A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 21.10
- Ubuntu 20.04 LTS
- Ubuntu 18.04 LTS
- Ubuntu 16.04 ESM

Summary:

Several security issues were fixed in Zsh.

Software Description:
- zsh: shell with lots of features

Details:

Sam Foxman discovered that Zsh incorrectly handled certain inputs.
An attacker could possibly use this issue to regain dropped privileges.
(CVE-2019-20044)

It was discovered that Zsh incorrectly handled certain inputs.
An attacker could possibly use this issue to execute arbitrary code.
(CVE-2021-45444)

Update instructions:

The problem can be corrected by updating your system to the following
package versions:

Ubuntu 21.10:
zsh 5.8-6ubuntu0.1
zsh-static 5.8-6ubuntu0.1

Ubuntu 20.04 LTS:
zsh 5.8-3ubuntu1.1
zsh-static 5.8-3ubuntu1.1

Ubuntu 18.04 LTS:
zsh 5.4.2-3ubuntu3.2
zsh-static 5.4.2-3ubuntu3.2

Ubuntu 16.04 ESM:
zsh 5.1.1-1ubuntu2.3+esm1
zsh-static 5.1.1-1ubuntu2.3+esm1

In general, a standard system update will make all the necessary changes.

References:
https://ubuntu.com/security/notices/USN-5325-1
CVE-2019-20044, CVE-2021-45444

Package Information:
https://launchpad.net/ubuntu/+source/zsh/5.8-6ubuntu0.1
https://launchpad.net/ubuntu/+source/zsh/5.8-3ubuntu1.1
https://launchpad.net/ubuntu/+source/zsh/5.4.2-3ubuntu3.2