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

Severity: critical (CVSS 9.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.4% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2026-06-22 · updated 2026-10-25
Weakness: CWE-416

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.

Affected products

xmlsoft libxml2: from 2.9.11 through 2.11.0

References

https://bugs.launchpad.net/ubuntu/+source/libxml2/+bug/2141260
https://gitlab.gnome.org/GNOME/libxml2/-/work_items/1058

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