Arbitrary Code Execution via Heap-based Buffer Overflow

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. Fixed by RHSA-2026:30647 — update the affected packages (`sudo dnf update`). Affected Red Hat products: Red Hat Hardened Images. Will not fix / out of support: Red Hat Enterprise Linux 6.