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.
Affected products
microsoft: xml notepad
References5
- github.com/microsoft/XmlNotepad/security/advisories/GHSA-5j32-4… MitigationVendor Advisory
- github.com/microsoft/XmlNotepad/security/advisories/GHSA-5j32-4… MitigationVendor Advisory
- github.com/microsoft/XmlNotepad/commit/3665603d61ba10b7827a3724… Patch
- github.com/microsoft/XmlNotepad/commit/c03ab2311ac6960452eb1ab4… Patch
- github.com/microsoft/XmlNotepad/releases/tag/2.9.0.21 ProductRelease Notes
Metrics
- CVSS 3.1
-
6.5
MEDIUM
Score source: CNA
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N - EPSS — exploit probability
- 1% percentile: 64 · as of 12 November 2026
- CWE
- CWE-611
Could this be exploited in your environment?
A patch closes the known hole. A penetration test shows what an attacker can still reach — with proof.