=========================================================================
Ubuntu Security Notice USN-5225-1
January 12, 2022

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

- Ubuntu 21.10
- Ubuntu 21.04
- Ubuntu 20.04 LTS
- Ubuntu 18.04 LTS
- Ubuntu 16.04 ESM
- Ubuntu 14.04 ESM

Summary:

lxml could be made to execute arbitrary code if it received a specially crafted XML
or HTML file.

Software Description:
- lxml: pythonic binding for the libxml2 and libxslt libraries

Details:

It was discovered that lxml incorrectly handled certain XML and HTML files.
An attacker could possibly use this issue to execute arbitrary code.

Update instructions:

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

Ubuntu 21.10:
  python3-lxml                    4.6.3+dfsg-0.1ubuntu0.2

Ubuntu 21.04:
  python3-lxml                    4.6.3-1ubuntu0.2

Ubuntu 20.04 LTS:
  python-lxml                     4.5.0-1ubuntu0.5
  python3-lxml                    4.5.0-1ubuntu0.5

Ubuntu 18.04 LTS:
  python-lxml                     4.2.1-1ubuntu0.6
  python3-lxml                    4.2.1-1ubuntu0.6

Ubuntu 16.04 ESM:
  python-lxml                     3.5.0-1ubuntu0.4+esm2
  python3-lxml                    3.5.0-1ubuntu0.4+esm2

Ubuntu 14.04 ESM:
  python-lxml                     3.3.3-1ubuntu0.2+esm5
  python3-lxml                    3.3.3-1ubuntu0.2+esm5

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

References:
  https://ubuntu.com/security/notices/USN-5225-1
  CVE-2021-43818

Package Information:
  https://launchpad.net/ubuntu/+source/lxml/4.6.3+dfsg-0.1ubuntu0.2
  https://launchpad.net/ubuntu/+source/lxml/4.6.3-1ubuntu0.2
  https://launchpad.net/ubuntu/+source/lxml/4.5.0-1ubuntu0.5
  https://launchpad.net/ubuntu/+source/lxml/4.2.1-1ubuntu0.6