Medium [CVE-2026-56132] Arbitrary Code Execution via Heap-based Buffer Overflow
This medium-severity Red Hat Linux advisory covers CVE-2026-56132 affecting Red Hat Hardened Images, Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 6.
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Summary
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. 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. Red Hat severity: Moderate — CVSS 6.9 (CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:L).
Weakness: CWE-131. 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.
Will not fix / out of support: Red Hat Enterprise Linux 6. Red Hat fixing advisory: RHSA-2026:30647.
- < 2.8.2
Official advisory · high-confidence parse· fetched 17 days ago·verify at source
- expat-main-2.8.2-1.hum1
- RHSA-2026:30647
Official advisory · high-confidence parse· fetched 17 days ago·verify at source
Mitigation
Upgrade to a fixed release: expat-main-2.8.2-1.hum1, RHSA-2026:30647. That is the remediation for this advisory.
The vendor advisory may list additional interim mitigations or workarounds not captured here — review it before change work.
Official advisory · high-confidence parse· fetched 17 days ago·verify at source
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