XML Notepad is a Windows program that provides a simple intuitive User Interface for browsing and editing XML documents. Prior to version 2.9.0.21, XML Notepad does not disable DTD processing by default which means external entities are resolved automatically. There is a well known attack related to malicious DTD files where an attacker to craft a malicious XML file that loads a DTD that causes XML Notepad to make outbound HTTP/SMB requests, potentially leaking local file contents or capturing the victim's NTLM credentials. This issue has been patched in version 2.9.0.21.

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History

Wed, 01 Apr 2026 02:15:00 +0000

Type Values Removed Values Added
Description XML Notepad is a Windows program that provides a simple intuitive User Interface for browsing and editing XML documents. Prior to version 2.9.0.21, XML Notepad does not disable DTD processing by default which means external entities are resolved automatically. There is a well known attack related to malicious DTD files where an attacker to craft a malicious XML file that loads a DTD that causes XML Notepad to make outbound HTTP/SMB requests, potentially leaking local file contents or capturing the victim's NTLM credentials. This issue has been patched in version 2.9.0.21.
Title XML Notepad: XML External Entity (XXE) Injection via Unsafe XmlTextReader in XML Diff and Schema Loading
Weaknesses CWE-611
References
Metrics cvssV3_1

{'score': 6.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N'}


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cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-03-31T21:05:50.647Z

Reserved: 2026-03-27T13:45:29.620Z

Link: CVE-2026-34401

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-03-31T22:16:18.490

Modified: 2026-03-31T22:16:18.490

Link: CVE-2026-34401

cve-icon Redhat

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cve-icon OpenCVE Enrichment

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Weaknesses