A HTMLDOC security update has been released for Ubuntu 20.04 LTS and 21.04.

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Ubuntu Security Notice USN-5198-1
December 16, 2021

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

- Ubuntu 21.04
- Ubuntu 20.04 LTS

Summary:

HTMLDOC could be made to crash if it received specially crafted
input.

Software Description:
- htmldoc: HTML processor that generates indexed HTML, PS, and PDF

Details:

It was discovered that HTMLDOC improperly handled malformed URIs from an input
html file. An attacker could use this to cause a denial of service.

Update instructions:

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

Ubuntu 21.04:
htmldoc 1.9.11-2ubuntu0.1
htmldoc-common 1.9.11-2ubuntu0.1

Ubuntu 20.04 LTS:
htmldoc 1.9.7-1ubuntu0.2
htmldoc-common 1.9.7-1ubuntu0.2

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

References:
https://ubuntu.com/security/notices/USN-5198-1
CVE-2021-23180

Package Information:
https://launchpad.net/ubuntu/+source/htmldoc/1.9.11-2ubuntu0.1
https://launchpad.net/ubuntu/+source/htmldoc/1.9.7-1ubuntu0.2