Medium [CVE-2026-6653] Denial of Service via crafted XML input due to use-after-free
This medium-severity Red Hat Linux advisory covers CVE-2026-6653 affecting Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9, Red Hat Discovery 2.
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Summary
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. A flaw was found in libxml2.
This improper handling of entity resolution can lead to a denial-of-service (DoS), making the affected system or application unavailable. This Moderate impact use-after-free vulnerability in libxml2 can lead to a denial of service in Red Hat products that process untrusted XML input.
In the worst-case scenario, a remote attacker is able to provide specially crafted XML, which, if parsed by an affected application, could cause the application to crash. Red Hat severity: Moderate — CVSS 5.9 (CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H).
Weakness: CWE-416. Affected Red Hat products: Red Hat Enterprise Linux 8; Red Hat Enterprise Linux 9; Red Hat Discovery 2; Red Hat Update Infrastructure 5; Red Hat OpenShift Container Platform 4.
Red Hat lists Red Hat Enterprise Linux 10; Red Hat Enterprise Linux 6; Red Hat Enterprise Linux 7; Red Hat Hardened Images as not affected. Red Hat fixing advisory: RHSA-2026:69655, RHSA-2026:61247, RHSA-2026:61783, RHSA-2026:66018.
Affected products named by the advisory: Red Hat package: libxml2.
Affected versions
No affected-version range was extracted from the source record. The vendor advisory is authoritative — check it before change work.
Official advisory · high-confidence parse· fetched 22 days ago·verify at source
- libxml2-0:2.9.7-21.el8_10.8
- libxml2-0:2.9.13-14.el9_8.4
- discovery/discovery-server-rhel9:1788205779
- rhui5/cds-kubernetes-rhel9:1788880445
- rhui5/cds-rhel9:1788880464
- rhui5/haproxy-rhel9:1788880456
- rhui5/installer-rhel9:1788765051
- rhui5/rhua-rhel9:1788880581
- RHSA-2026:69655
- RHSA-2026:61247
- RHSA-2026:61783
- RHSA-2026:66018
Official advisory · high-confidence parse· fetched 22 days ago·verify at source
Mitigation checklist
- Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability. Updating to a fixed version of libxml2 (2.11.0 or later upstream, or a future RHEL errata) will fully resolve this issue.
Official advisory · high-confidence parse· fetched 22 days ago·verify at source
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