CVE-2026-76781

Publication date 17 September 2026

Last updated 8 October 2026

Ubuntu priority

Cvss 3 Severity Score

Description

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).

Read the notes from the security team

Status

Show unmaintained releases

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

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Notes

charlescochran

The vulnerable nextCatalog dedup loop was added by the upstream fix for CVE-2026-0992, which we backported to every supported release, so all releases are affected.

Patch details

For informational purposes only. We recommend not to cherry-pick updates. How can I get the fixes?

Package	Patch details
libxml2	Upstream: a34c084

Severity score breakdown

CVSS version: CVSS v3.0

Base score 5.5 · Medium

Base metrics

Parameter	Value
Attack vector	Local
Attack complexity	Low
Privileges required	None
User interaction	Required
Scope	Unchanged
Confidentiality impact	None
Integrity impact	None
Availability impact	High

Scores

Parameter	Value
Base score	5.5 · Medium
Exploitability score	-
Impact score	-