libxml2 vulnerabilities

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)