A HTML Tidy security update has been released for Ubuntu Linux 20.04 LTS, 22.04 LTS, 23.04, and 23.10.

[USN-6483-1] HTML Tidy vulnerability

==========================================================================
Ubuntu Security Notice USN-6483-1
November 15, 2023

tidy-html5 vulnerability
==========================================================================

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

- Ubuntu 23.10
- Ubuntu 23.04
- Ubuntu 22.04 LTS
- Ubuntu 20.04 LTS

Summary:

tidy-html5 could be made to crash or run programs if it opened a specially
crafted file.

Software Description:
- tidy-html5: HTML/XML syntax checker and reformatter

Details:

Neeraj Pal discovered that HTML Tidy incorrectly handled parsing certain
HTML data. If a user or automated system were tricked into parsing
specially crafted HTML data, a remote attacker could cause HTML Tidy to
consume resources, leading to 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 23.10:
libtidy5deb1 2:5.6.0-11ubuntu0.23.10.1
tidy 2:5.6.0-11ubuntu0.23.10.1

Ubuntu 23.04:
libtidy5deb1 2:5.6.0-11ubuntu0.23.04.1
tidy 2:5.6.0-11ubuntu0.23.04.1

Ubuntu 22.04 LTS:
libtidy5deb1 2:5.6.0-11ubuntu0.22.04.1
tidy 2:5.6.0-11ubuntu0.22.04.1

Ubuntu 20.04 LTS:
libtidy5deb1 2:5.6.0-11ubuntu0.20.04.1
tidy 2:5.6.0-11ubuntu0.20.04.1

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

References:
https://ubuntu.com/security/notices/USN-6483-1
CVE-2021-33391

Package Information:
https://launchpad.net/ubuntu/+source/tidy-html5/2:5.6.0-11ubuntu0.23.10.1
https://launchpad.net/ubuntu/+source/tidy-html5/2:5.6.0-11ubuntu0.23.04.1
https://launchpad.net/ubuntu/+source/tidy-html5/2:5.6.0-11ubuntu0.22.04.1
https://launchpad.net/ubuntu/+source/tidy-html5/2:5.6.0-11ubuntu0.20.04.1