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CVE-2025-6021

libxml2: Integer Overflow in xmlBuildQName() Leads to Stack Buffer Overflow in libxml2

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Severity

Moderate

Red Hat Product Security

7.5

CVSS 3.1

Review impact separately from score.

Published · June 12, 2025

Updated · October 13, 2026

Description

A flaw was found in libxml2's xmlBuildQName function, where integer overflows in buffer size calculations can lead to a stack-based buffer overflow. This issue can result in memory corruption or a denial of service when processing crafted input.

Statement

This vulnerability is rated Moderate due to the lack of confidentiality impact and limited integrity concerns, with the main risk being potential denial-of-service from a crash. Exploitation requires crafted XML input and specific application behavior using xmlBuildQName. While it’s a write overflow, modern mitigations make remote code execution unlikely.

CVSS score applicability

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

Mitigation

Mitigation for this issue is either not available or the currently available options don't meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability. Users are strongly advised to apply vendor-supplied patches as soon as they become available to address the underlying integer overflow flaw in the affected code.

CVSS / CWE

CVSS 3.1 · 7.5
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CWE-787 · Out-of-bounds Write