Bug 2490669 (CVE-2026-56132)

Summary: CVE-2026-56132 expat: libexpat: Arbitrary Code Execution via Heap-based Buffer Overflow
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: gotiwari, jhorak, mvyas, rhel-process-autobot, watson-tool-maintainers
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in libexpat, a library used for parsing XML data. An attacker could exploit a heap-based buffer overflow, a type of memory error, by providing specially crafted XML input. This vulnerability occurs when the library mishandles memory reallocation while processing XML, particularly when multiple parsers share data. Successful exploitation could allow the attacker to execute arbitrary code, access sensitive information, or cause the application to crash, leading to a denial of service.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Bug Depends On: 2493638, 2493639    
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Description OSIDB Bzimport 2026-06-19 05:01:29 UTC 
In libexpat before 2.8.2, there is a heap-based buffer overflow in doProlog in xmlparse.c because scaffold backing array reallocation is mishandled when there is data-structure sharing across parsers.