CVE-2026-76781 Red Hat CVE debrief

Who should care

Defenders responsible for systems and applications using libxml2 for XML catalog parsing should assess exposure and prioritize remediation, especially for systems handling untrusted XML catalog inputs.

Why it matters

CVE-2026-76781 is a medium-severity vulnerability in libxml2 that can cause a Denial of Service (DoS) when parsing specially crafted XML catalogs. Defenders responsible for systems using libxml2 should assess exposure, especially for systems handling untrusted XML catalog inputs, and prioritize remediation. The vulnerability's impact is currently limited by sparse evidence on affected versions and exploitation, requiring verification from official sources.

• Denial of Service (DoS) due to application crash
• Potential for increased latency or resource utilization due to parsing issues
• Need for verification of affected versions and remediation status
• Possible impact on data processing or system availability

Technical summary

The libxml2 library is vulnerable to a Denial of Service (DoS) attack when parsing a specially crafted XML catalog. The vulnerability occurs when a `nextCatalog` element lacks its mandatory `catalog` attribute, leading to a NULL pointer dereference and application crash. This issue can be triggered by a local user or an attacker providing a malicious XML catalog. The vulnerability affects systems and applications using libxml2 for XML catalog parsing, particularly those handling untrusted XML catalog inputs. Defenders should review vendor guidance for remediation and verify the presence of libxml2 in their environments.

Defensive priority

Assess exposure and prioritize remediation for systems using libxml2, especially those parsing XML catalogs from untrusted sources.

Recommended defensive actions

• Assess exposure by identifying systems and applications using libxml2 for XML catalog parsing.
• Prioritize remediation for systems parsing XML catalogs from untrusted sources.
• Monitor for and restrict untrusted XML catalog inputs.
• Review compensating controls for exposed systems while remediation is scheduled and verified.
• Check relevant monitoring, detection, and logs for exposed assets that need extra review.
• Track exceptions, retest remediated assets, and close the item only after evidence is documented.
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up.

Evidence notes

The CVE record and NVD entry provide details on the vulnerability, but additional information on affected versions and remediation is limited. The libxml2 library is widely used in various applications and systems for XML parsing. Defenders should verify the presence of libxml2 in their environments, especially in systems handling untrusted XML catalog inputs, and review vendor guidance for remediation. The vulnerability's impact is currently limited by sparse evidence on affected versions and exploitation, requiring verification from

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.