A PHP security update has been released for Ubuntu 20.04 LTS and 21.10.

USN-5303-1: PHP vulnerability

==========================================================================
Ubuntu Security Notice USN-5303-1
February 28, 2022

php7.4, php8.0 vulnerability
==========================================================================

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

- Ubuntu 21.10
- Ubuntu 20.04 LTS

Summary:

PHP could be made to crash or run programs if it received specially crafted
input.

Software Description:
- php8.0: HTML-embedded scripting language interpreter
- php7.4: HTML-embedded scripting language interpreter

Details:

It was discovered that PHP incorrectly handled certain scripts.
An attacker could possibly use this issue to cause a denial of service,
or possibly execute arbitrary code.

Update instructions:

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

Ubuntu 21.10:
php8.0-cgi 8.0.8-1ubuntu0.2
php8.0-cli 8.0.8-1ubuntu0.2
php8.0-fpm 8.0.8-1ubuntu0.2

Ubuntu 20.04 LTS:
php7.4-cgi 7.4.3-4ubuntu2.9
php7.4-cli 7.4.3-4ubuntu2.9
php7.4-fpm 7.4.3-4ubuntu2.9

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

References:
https://ubuntu.com/security/notices/USN-5303-1
CVE-2021-21708

Package Information:
https://launchpad.net/ubuntu/+source/php8.0/8.0.8-1ubuntu0.2
https://launchpad.net/ubuntu/+source/php7.4/7.4.3-4ubuntu2.9