Bug 2520125 (CVE-2026-76957)

Summary: CVE-2026-76957 libexpat: libexpat: Memory corruption vulnerability allows arbitrary code execution or denial of service
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: akhatavk, aos-team-art-private, asdas, crizzo, dpaolell, gotiwari, gtanzill, jbuscemi, jdelft, jhorak, jupierce, kshier, lgarciaa, mbiarnes, mvyas, ppalepu, ppostler, prdhamdh, rhel-process-autobot, sghai, sidsharm, stcannon, suppawar, teagle, 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 libexpat. The library's handling of custom encoding callbacks lacks proper tracking of handler call depth, which can lead to a use-after-free vulnerability. This memory corruption flaw could allow a local attacker to cause a denial of service or potentially execute arbitrary code.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Bug Depends On: 2524648, 2524649    
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Description OSIDB Bzimport 2026-08-20 04:41:20 UTC
libexpat before 2.8.4 lacks handler call depth tracking with custom encoding callbacks. Thus, a use-after-free can occur. NOTE: this is similar to CVE-2026-50219, CVE-2026-56131 and CVE-2026-56412.