CVE-2026-34401

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.
Configurations

Configuration 1 (hide)

cpe:2.3:a:microsoft:xml_notepad:*:*:*:*:*:windows:*:*

History

24 Jul 2026, 21:10

Type Values Removed Values Added
Summary
  • (es) XML Notepad es un programa de Windows que proporciona una interfaz de usuario sencilla e intuitiva para navegar y editar documentos XML. Antes de la versión 2.9.0.21, XML Notepad no deshabilita el procesamiento de DTD por defecto, lo que significa que las entidades externas se resuelven automáticamente. Existe un ataque bien conocido relacionado con archivos DTD maliciosos donde un atacante puede crear un archivo XML malicioso que carga un DTD que hace que XML Notepad realice solicitudes HTTP/SMB salientes, potencialmente filtrando el contenido de archivos locales o capturando las credenciales NTLM de la víctima. Este problema ha sido parcheado en la versión 2.9.0.21.

13 Apr 2026, 15:19

Type Values Removed Values Added
CPE cpe:2.3:a:microsoft:xml_notepad:*:*:*:*:*:windows:*:*
References () https://github.com/microsoft/XmlNotepad/commit/3665603d61ba10b7827a3724e854748cb780140c - () https://github.com/microsoft/XmlNotepad/commit/3665603d61ba10b7827a3724e854748cb780140c - Patch
References () https://github.com/microsoft/XmlNotepad/commit/c03ab2311ac6960452eb1ab49098768f851dcc53 - () https://github.com/microsoft/XmlNotepad/commit/c03ab2311ac6960452eb1ab49098768f851dcc53 - Patch
References () https://github.com/microsoft/XmlNotepad/releases/tag/2.9.0.21 - () https://github.com/microsoft/XmlNotepad/releases/tag/2.9.0.21 - Product, Release Notes
References () https://github.com/microsoft/XmlNotepad/security/advisories/GHSA-5j32-486h-42ch - () https://github.com/microsoft/XmlNotepad/security/advisories/GHSA-5j32-486h-42ch - Mitigation, Vendor Advisory
First Time Microsoft xml Notepad
Microsoft

01 Apr 2026, 17:28

Type Values Removed Values Added
References () https://github.com/microsoft/XmlNotepad/security/advisories/GHSA-5j32-486h-42ch - () https://github.com/microsoft/XmlNotepad/security/advisories/GHSA-5j32-486h-42ch -

31 Mar 2026, 22:16

Type Values Removed Values Added
New CVE

Information

Published : 2026-03-31 22:16

Updated : 2026-07-24 21:10


NVD link : CVE-2026-34401

Mitre link : CVE-2026-34401

CVE.ORG link : CVE-2026-34401


JSON object : View

Products Affected

microsoft

  • xml_notepad
CWE
CWE-611

Improper Restriction of XML External Entity Reference