CVE-2026-34401

6.5 MEDIUM
Published: March 31, 2026 Modified: April 13, 2026
View on NVD

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.

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CVSS v3.x Details

0.0 Low Medium High Critical 10.0
Vector String
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N

References to Advisories, Solutions, and Tools

Patch Vendor Advisory Exploit Third Party Advisory
https://github.com/microsoft/XmlNotepad/releases/tag/2.9.0.21
Source: security-advisories@github.com
Product Release Notes
https://github.com/microsoft/XmlNotepad/security/advisories/GHSA-5j32-486h-42ch
Source: security-advisories@github.com
Mitigation Vendor Advisory
https://github.com/microsoft/XmlNotepad/security/advisories/GHSA-5j32-486h-42ch
Source: 134c704f-9b21-4f2e-91b3-4a467353bcc0
Mitigation Vendor Advisory

5 reference(s) from NVD

Quick Stats

CVSS v3 Score
6.5 / 10.0
EPSS (Exploit Probability)
0.3%
53th percentile
Exploitation Status
Not in CISA KEV

Weaknesses (CWE)

Affected Vendors

microsoft