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National Vulnerability Database

National Vulnerability Database

NVD

National Vulnerability Database
  1. Vulnerabilities

CVE-2026-34401 Detail

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.


Metrics

 
NVD enrichment efforts reference publicly available information to associate vector strings. CVSS information contributed by other sources is also displayed.
CVSS 4.0 Severity and Vector Strings:

NIST CVSS score
NIST: NVD
N/A
NVD assessment not yet provided.

References to Advisories, Solutions, and Tools

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URL Source(s) Tag(s)
https://github.com/microsoft/XmlNotepad/commit/3665603d61ba10b7827a3724e854748cb780140c GitHub, Inc. Patch 
https://github.com/microsoft/XmlNotepad/commit/c03ab2311ac6960452eb1ab49098768f851dcc53 GitHub, Inc. Patch 
https://github.com/microsoft/XmlNotepad/releases/tag/2.9.0.21 GitHub, Inc. Product  Release Notes 
https://github.com/microsoft/XmlNotepad/security/advisories/GHSA-5j32-486h-42ch CISA-ADP, GitHub, Inc. Mitigation  Vendor Advisory 

Weakness Enumeration

CWE-ID CWE Name Source
CWE-611 Improper Restriction of XML External Entity Reference GitHub, Inc.  

Known Affected Software Configurations Switch to CPE 2.2

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Change History

6 change records found show changes

Quick Info

CVE Dictionary Entry:
CVE-2026-34401
NVD Published Date:
03/31/2026
NVD Last Modified:
07/24/2026
Source:
GitHub, Inc.