ZeroDay Findings
Sign inSign up

Findings

Vulnerability · 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 · corrected/updated Jul 24, 2026 · microsoft xml notepad · evidence confidence high

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.

Grounded briefings

Catalog interpretations for three audiences. Each brief cites ingested metadata and the original advisories below. They are not independent research and they do not invent exploit steps.

Executive

CVE-2026-34401 is a medium public vulnerability record for microsoft xml notepad. It is not currently listed in the CISA Known Exploited catalog. Check the linked vendor or CERT advisories for patch status. This summary is a catalog interpretation of the ingested metadata and cites the original advisories below.

System administrator

Identify whether microsoft xml notepad is in your estate, then compare installed versions with the affected ranges. Affected packages or ranges on record: microsoft/xml notepad. Check the linked vendor or CERT advisories for patch status. Prefer the vendor or distribution advisory linked in Sources before changing production systems. This is a catalog interpretation, not a runbook.

Security analyst

Signals on file: CVSS 6.5 (technical impact); EPSS 1.4% (30-day exploitation probability). It is not currently listed in the CISA Known Exploited catalog. Weakness classes: CWE-611. Sources contributing to this record: cve_org, epss, nvd. Public exploit references, when present, are outbound links only and are not proof of active exploitation. This is a catalog interpretation of stored metadata.

Exploitation and remediation

  • Exploitation evidence

    Not listed as known exploited in CISA KEV. Not in CISA KEV or VulnCheck KEV.

  • Patch and remediation

    A patch or advisory reference is linked. Open the original publisher for availability by product version.

  • Safe detection guidance

    Compare installed versions with the affected ranges below and verify the advisory from the original publisher. This site stores metadata and outbound links only; it does not ship exploit code or proof-of-concept payloads.

Technology hubs

Windows

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
  • FIRST EPSSExploitation probabilityCVE-2026-34401

    30-day exploitation probability 1.4%

    first.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