Bug 2519776 (CVE-2026-76781)

Summary: CVE-2026-76781 libxml2: libxml2: NULL pointer dereference parsing nextCatalog without catalog attribute
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: akhatavk, aos-team-art-private, asdas, dpaolell, gbenhaim, gtanzill, jbuscemi, jdelft, jupierce, kaycoth, kshier, lgarciaa, mbiarnes, niyer, ppalepu, ppostler, prdhamdh, rhel-process-autobot, sghai, sidsharm, stcannon, suppawar, teagle, twaugh, vlaad, watson-tool-maintainers, yguenane
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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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).
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
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Bug Depends On: 2519777, 2519778, 2519779, 2519780, 2519781, 2519782, 2519783    
Bug Blocks:    

Description OSIDB Bzimport 2026-08-19 17:25:23 UTC
A NULL pointer dereference flaw was found in libxml2 XML catalog parsing. When a catalog contains a nextCatalog element without the mandatory catalog attribute, xmlParseXMLCatalogOneNode() returns NULL, but the nextCatalog deduplication loop dereferences the entry before the existing NULL check, crashing the application.