Medium [CVE-2026-76781] Libxml2: libxml2: null pointer dereference parsing nextcatalog without catalog attribute
This medium-severity Red Hat Linux advisory covers CVE-2026-76781 affecting Red Hat Hardened Images, Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 6.
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Summary
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). This Moderate flaw in libxml2's XML catalog parsing can lead to a denial of service.
The vulnerability requires user interaction, as a specially crafted XML catalog with a missing `catalog` attribute in a `nextCatalog` element must be processed by an application using libxml2, causing it to crash. This limits the attack surface to scenarios where an attacker can provide malicious XML input to a vulnerable application.
Red Hat severity: Moderate — CVSS 5.5 (CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H). Weakness: CWE-476.
Affected Red Hat products: 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. Red Hat lists Red Hat Hardened Images as not affected.
Will not fix / out of support: Red Hat Enterprise Linux 6; Red Hat Enterprise Linux 7. Red Hat fixing advisory: RHSA-2026:57604.
Affected products named by the advisory: Red Hat package: libxml2; Red Hat package: podman.
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 13 days ago·verify at source
- libxml2-main-2.15.3-0.1.3.hum1
- RHSA-2026:57604
Official advisory · high-confidence parse· fetched 13 days ago·verify at source
Mitigation checklist
- To mitigate this issue, avoid processing untrusted XML catalog files with applications linked against libxml2. Users should exercise caution when opening or processing XML documents from untrusted sources, as a malicious catalog could lead to application crashes. Where possible, restrict the ability of applications to load external XML catalogs, or ensure that only trusted catalog files are used.
Official advisory · high-confidence parse· fetched 13 days ago·verify at source
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