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Findings

CVE-2026-34401

XML Notepad is a Windows program that provides a simple intuitive User Interface for browsing and editing XML documents.

Published Mar 31, 2026 · updated Jul 24, 2026 · microsoft xml notepad

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.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Mar 31, 2026 · NIST NVD

    Detected

    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 XM

  2. Jul 24, 2026 · NIST NVD

    Updated

    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 XM

Affected

  • cpe microsoft/xml notepadversion unspecified

Sources

  • CVE.orgVulnerability recordCVE-2026-34401

    Official CVE identifier

    cve.org
  • NIST NVDVulnerability recordCVE-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 kno

    nvd.nist.gov

References