CVE-2026-34401
MediumCVSS 6.5Exploitation Probability (EPSS)
Elevated risk59th percentile - higher than 59% of all known CVEs
Summary
In XML Notepad for Windows prior to version 2.9.0.21, DTD processing is not disabled by default, allowing automatic resolution of external entities. An attacker can craft a malicious XML file that loads a DTD causing outbound HTTP/SMB requests, potentially leaking local file contents or capturing NTLM credentials. The issue is fixed in version 2.9.0.21.
Risk Assessment
A user opening a malicious XML file may cause leakage of sensitive data or capture of NTLM credentials, enabling further network attacks.
Recommendation
Immediately update XML Notepad to version 2.9.0.21 or later.
Original NVD description (English source)
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.