CVE-2026-34401 is an XML External Entity (XXE) vulnerability affecting XML Notepad versions prior to 2.9.0.21, stemming from its default processing of DTDs which resolves external entities. Rated Medium severity (CVSS 6.5), this vulnerability allows an unauthenticated attacker to craft a malicious XML file. When opened by a victim, this file can trigger outbound HTTP/SMB requests, potentially leading to the leakage of local file contents or the capture of NTLM credentials. User interaction is required for exploitation. There is currently no evidence of active exploitation, nor are public exploit codes or significant community discussion available for this vulnerability.
| Vendor | Product | Version(s) | CPE |
|---|---|---|---|
< 2.9.0.21CPE matchmatch criteria | cpe:2.3:a:microsoft:xml_notepad:*:*:*:*:*:windows:*:* |
CVSS version used by this source: 3.1
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
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