CVE-2026-76781 — Libxml2: libxml2: null pointer dereference parsing nextcatalog without catalog attribute

Affected: Red Hat Hardened Images, Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 7, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9, Red Hat OpenShift Container Platform 4

A flaw was found in libxml2. A local user or an attacker providing a specially crafted XML catalog can trigger a NULL pointer dereference during XML catalog parsing. This occurs when a `nextCatalog` element lacks its mandatory `catalog` attribute, leading to the application crashing and causing a Denial of Service (DoS).

USN-8910-1 — libxml2 vulnerabilities

Affected: Ubuntu:Pro:14.04:LTS: libxml2, Ubuntu:Pro:16.04:LTS: libxml2, Ubuntu:Pro:18.04:LTS: libxml2, Ubuntu:Pro:20.04:LTS: libxml2, Ubuntu:22.04:LTS: libxml2, Ubuntu:24.04:LTS: libxml2, Ubuntu:26.04:LTS: libxml2

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…

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CVE-2026-76781 — Libxml2: libxml2: null pointer dereference parsing nextcatalog without catalog attribute

USN-8910-1 — libxml2 vulnerabilities