CVE-2026-21249: CWE-73: External Control of File Name or Path in Microsoft Windows 10 Version 1607
External control of file name or path in Windows NTLM allows an unauthorized attacker to perform spoofing locally.
AI Analysis
Technical Summary
This vulnerability, tracked as CVE-2026-21249 and categorized under CWE-73 (External Control of File Name or Path), affects Windows 10 Version 1607 (build 10.0.14393.0). It involves improper handling of file names or paths in the NTLM authentication process, enabling a local attacker without privileges to perform spoofing. The CVSS 3.1 vector indicates low attack complexity, no privileges required, and user interaction needed, with limited confidentiality impact and no integrity or availability impact. Microsoft has published an official fix to remediate this vulnerability.
Potential Impact
The impact is limited to local spoofing attacks that could mislead users or processes by manipulating file names or paths. The confidentiality impact is low, and there is no impact on integrity or availability. No known exploits are reported in the wild.
Mitigation Recommendations
An official fix is available from Microsoft. Users and administrators should apply the security update provided in the Microsoft advisory at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21249 to remediate this vulnerability.
CVE-2026-21249: CWE-73: External Control of File Name or Path in Microsoft Windows 10 Version 1607
Description
External control of file name or path in Windows NTLM allows an unauthorized attacker to perform spoofing locally.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
This vulnerability, tracked as CVE-2026-21249 and categorized under CWE-73 (External Control of File Name or Path), affects Windows 10 Version 1607 (build 10.0.14393.0). It involves improper handling of file names or paths in the NTLM authentication process, enabling a local attacker without privileges to perform spoofing. The CVSS 3.1 vector indicates low attack complexity, no privileges required, and user interaction needed, with limited confidentiality impact and no integrity or availability impact. Microsoft has published an official fix to remediate this vulnerability.
Potential Impact
The impact is limited to local spoofing attacks that could mislead users or processes by manipulating file names or paths. The confidentiality impact is low, and there is no impact on integrity or availability. No known exploits are reported in the wild.
Mitigation Recommendations
An official fix is available from Microsoft. Users and administrators should apply the security update provided in the Microsoft advisory at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21249 to remediate this vulnerability.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- microsoft
- Date Reserved
- 2025-12-11T21:02:05.736Z
- Cvss Version
- 3.1
- State
- PUBLISHED
- Remediation Level
- official-fix
- Vendor Advisory Urls
- [{"url":"https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21249","vendor":"Microsoft"}]
Threat ID: 698b76004b57a58fa120a029
Added to database: 2/10/2026, 6:16:32 PM
Last enriched: 5/12/2026, 5:12:42 AM
Last updated: 5/22/2026, 8:34:47 PM
Views: 135
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