USN-8910-1: libxml2 vulnerabilities

Publication date

8 October 2026

Overview

Several security issues were fixed in libxml2.


Packages

Details

Yirou Yang discovered that libxml2 incorrectly handled certain XML
catalogs. If a user or automated system was tricked into processing a
specially crafted XML catalog, an attacker could possibly use this issue to
cause libxml2 to crash, resulting in a denial of service. (CVE-2026-76781)

It was discovered that libxml2 incorrectly handled certain large qualified
names, leading to a heap-based buffer overflow. An attacker could possibly
use this issue to cause libxml2 to crash, resulting in a denial of service,
or possibly execute arbitrary code. (CVE-2026-86138)

It was discovered that libxml2 incorrectly handled escaping certain large
URI strings. An attacker could possibly use this issue to cause libxml2 to
use excessive resources, leading to a denial of service. This issue only
affected Ubuntu 26.04 LTS. (

Yirou Yang discovered that libxml2 incorrectly handled certain XML
catalogs. If a user or automated system was tricked into processing a
specially crafted XML catalog, an attacker could possibly use this issue to
cause libxml2 to crash, resulting in a denial of service. (CVE-2026-76781)

It was discovered that libxml2 incorrectly handled certain large qualified
names, leading to a heap-based buffer overflow. An attacker could possibly
use this issue to cause libxml2 to crash, resulting in a denial of service,
or possibly execute arbitrary code. (CVE-2026-86138)

It was discovered that libxml2 incorrectly handled escaping certain large
URI strings. An attacker could possibly use this issue to cause libxml2 to
use excessive resources, leading to a denial of service. This issue only
affected Ubuntu 26.04 LTS. (CVE-2026-86139)

Xudong Cao and Meng Xu discovered that libxml2 incorrectly handled certain
large XPointer expressions, leading to a heap-based buffer overflow. An
attacker could possibly use this issue to cause libxml2 to crash, resulting
in a denial of service, or possibly execute arbitrary code.
(CVE-2026-86142)

Xudong Cao and Meng Xu discovered that libxml2 did not check for integer
overflows before passing output lengths to write callbacks. An attacker
could possibly use this issue to cause an application using libxml2 to
crash, resulting in a denial of service. (CVE-2026-86143)

It was discovered that libxml2 did not apply parser options, such as
disabling network access, when processing XInclude directives under certain
circumstances. An attacker could possibly use this issue to perform XML
external entity injection or server-side request forgery attacks, or cause
a denial of service. (CVE-2026-86144)


Update instructions

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

Learn more about how to get the fixes.

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

Ubuntu Release Package Version
26.04 LTS resolute libxml2-16 –  2.15.2+dfsg-0.1ubuntu0.3
libxml2-dev –  2.15.2+dfsg-0.1ubuntu0.3
libxml2-source –  2.15.2+dfsg-0.1ubuntu0.3
24.04 LTS noble libxml2 –  2.9.14+dfsg-1.3ubuntu3.10
libxml2-dev –  2.9.14+dfsg-1.3ubuntu3.10
22.04 LTS jammy libxml2 –  2.9.13+dfsg-1ubuntu0.14
libxml2-dev –  2.9.13+dfsg-1ubuntu0.14
20.04 LTS focal libxml2 –  2.9.10+dfsg-5ubuntu0.20.04.10+esm6  
libxml2-dev –  2.9.10+dfsg-5ubuntu0.20.04.10+esm6  
18.04 LTS bionic libxml2 –  2.9.4+dfsg1-6.1ubuntu1.9+esm9  
libxml2-dev –  2.9.4+dfsg1-6.1ubuntu1.9+esm9  
16.04 LTS xenial libxml2 –  2.9.3+dfsg1-1ubuntu0.7+esm14  
libxml2-dev –  2.9.3+dfsg1-1ubuntu0.7+esm14  
14.04 LTS trusty libxml2 –  2.9.1+dfsg1-3ubuntu4.13+esm13  
libxml2-dev –  2.9.1+dfsg1-3ubuntu4.13+esm13  

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