==========================================================================
Ubuntu Security Notice USN-7974-1
January 22, 2026

libxml2 vulnerabilities
==========================================================================

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

- Ubuntu 25.10
- Ubuntu 24.04 LTS
- Ubuntu 22.04 LTS
- Ubuntu 20.04 LTS
- Ubuntu 18.04 LTS
- Ubuntu 16.04 LTS
- Ubuntu 14.04 LTS

Summary:

Several security issues were fixed in libxml2.

Software Description:
- libxml2: GNOME XML library

Details:

It was discovered that libxml2 incorrectly handled maliciously crafted SGML
catalog files. An attacker could possibly use this issue to cause libxml2
to consume excessive resources, leading to a denial of service.
(CVE-2025-8732)

It was discovered that libxml2 incorrectly handled recursive include
directories with the RelaxNG parser. An attacker could possibly use this
issue to cause libxml2 to consume excessive resources, leading to a denial
of service. (CVE-2026-0989)

Nick Wellnhofer discovered that libxml2 incorrectly parsed catalogs with
self-referencing URI delegates. An attacker could possibly use this issue
to cause libxml2 to consume excessive resources, leading to a denial of
service. (CVE-2026-0990)

Nick Wellnhofer discovered that libxml2 inefficiently parsed catalogs
linked with repeating nextCatalog elements. An attacker could possibly use
this issue to cause libxml2 to use excessive resources, leading to a denial
of service. (CVE-2026-0992)

Update instructions:

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

Ubuntu 25.10
  libxml2-16                      2.14.5+dfsg-0.2ubuntu0.1

Ubuntu 24.04 LTS
  libxml2                         2.9.14+dfsg-1.3ubuntu3.7

Ubuntu 22.04 LTS
  libxml2                         2.9.13+dfsg-1ubuntu0.11

Ubuntu 20.04 LTS
  libxml2                         2.9.10+dfsg-5ubuntu0.20.04.10+esm4
                                  Available with Ubuntu Pro

Ubuntu 18.04 LTS
  libxml2                         2.9.4+dfsg1-6.1ubuntu1.9+esm7
                                  Available with Ubuntu Pro

Ubuntu 16.04 LTS
  libxml2                         2.9.3+dfsg1-1ubuntu0.7+esm12
                                  Available with Ubuntu Pro

Ubuntu 14.04 LTS
  libxml2                         2.9.1+dfsg1-3ubuntu4.13+esm11
                                  Available with Ubuntu Pro

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

References:
  https://ubuntu.com/security/notices/USN-7974-1
  CVE-2025-8732, CVE-2026-0989, CVE-2026-0990, CVE-2026-0992

Package Information:
  https://launchpad.net/ubuntu/+source/libxml2/2.14.5+dfsg-0.2ubuntu0.1
  https://launchpad.net/ubuntu/+source/libxml2/2.9.14+dfsg-1.3ubuntu3.7
  https://launchpad.net/ubuntu/+source/libxml2/2.9.13+dfsg-1ubuntu0.11