CVE-2026-6653 libxml2: Use after free in xmlParseInternalSubset via improper entity resolution handling

High 7.0 Published 22 Jun 2026 Updated 22 Jun 2026

A remote attacker can cause a denial-of-service in libxml2 by sending maliciously crafted XML input that triggers a use-after-free error.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Over the internet
Victim action needed: Not needed
Fix: Available

What is CVE-2026-6653?

CVE-2026-6653 is a high-severity use after free vulnerability in Xmlsoft Libxml2, published on 22 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

Use After Free in libxml2's xmlParseInternalSubset from GNOME libxml2 version 2.9.11 to 2.11.0 allows a remote attacker to cause a denial-of-service via maliciously crafted XML input with improper entity resolution handling.

Weakness: CWE-611, CWE-416

Which versions are affected by CVE-2026-6653?

It affects 1 product.

Linux distribution packages (10)

`libxml2-debuginfo` Red Hat:enterprise_linux:8::appstream	All versions	`0:2.9.7-21.el8_10.8`
`libxml2-debugsource` Red Hat:enterprise_linux:8::appstream	All versions	`0:2.9.7-21.el8_10.8`
`libxml2-devel` Red Hat:enterprise_linux:8::appstream	All versions	`0:2.9.7-21.el8_10.8`
`python3-libxml2-debuginfo` Red Hat:enterprise_linux:8::appstream	All versions	`0:2.9.7-21.el8_10.8`
`libxml2` Red Hat:enterprise_linux:8::baseos	All versions	`0:2.9.7-21.el8_10.8`
`libxml2-debuginfo` Red Hat:enterprise_linux:8::baseos	All versions	`0:2.9.7-21.el8_10.8`
`libxml2-debugsource` Red Hat:enterprise_linux:8::baseos	All versions	`0:2.9.7-21.el8_10.8`
`python3-libxml2` Red Hat:enterprise_linux:8::baseos	All versions	`0:2.9.7-21.el8_10.8`
`python3-libxml2-debuginfo` Red Hat:enterprise_linux:8::baseos	All versions	`0:2.9.7-21.el8_10.8`
`libxml2` Rocky Linux:8	All versions	`0:2.9.7-21.el8_10.8`

Products include Xmlsoft Libxml2.

How do I fix CVE-2026-6653?

Upgrade to a fixed version.

Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.

Is CVE-2026-6653 being exploited?

There is no known exploitation of CVE-2026-6653 in the wild and no public exploit code.

All Xmlsoft Libxml2 vulnerabilities

Sources

Also known as BELL-CVE-2026-6653, CLSA-2026-1785316608, CLSA-2026-1785317036, CLSA-2026-1785317328, CLSA-2026-1787732374, CLSA-2026-1789473529 and 10 more.