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CVE-2026-34401

MEDIUM

6.5

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.

CVE Details

CVSS v3.1 Score6.5

SeverityMEDIUM

CVSS VectorCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N

Attack VectorNETWORK

ComplexityLOW

Privileges RequiredNONE

User InteractionREQUIRED

Published3/31/2026

Last Modified4/1/2026

Sourcenvd

Honeypot Sightings0

Weaknesses (CWE)

CWE-611

References

https://github.com/microsoft/XmlNotepad/commit/3665603d61ba10b7827a3724e854748cb780140c(security-advisories@github.com)

https://github.com/microsoft/XmlNotepad/commit/c03ab2311ac6960452eb1ab49098768f851dcc53(security-advisories@github.com)

https://github.com/microsoft/XmlNotepad/releases/tag/2.9.0.21(security-advisories@github.com)

https://github.com/microsoft/XmlNotepad/security/advisories/GHSA-5j32-486h-42ch(security-advisories@github.com)

https://github.com/microsoft/XmlNotepad/security/advisories/GHSA-5j32-486h-42ch(134c704f-9b21-4f2e-91b3-4a467353bcc0)

IOC Correlations

No correlations recorded

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