Unauthenticated privilege escalation via undisclosed NTLM flaw
Published Jan 14, 2025 · Updated Jun 9, 2026
Incorrect authentication in Windows NTLM V1 on Windows 11 24H2 and Windows Server 23H2 or 2025 allows remote attackers to elevate privileges. Microsoft has not published the authentication operation that mishandles untrusted input or the resulting privilege level. Exploitation requires network access and no credentials or user interaction; the elevated privilege level and concrete post-authentication actions remain unspecified.
Summary
What happened
Incorrect authentication in Windows NTLM V1 on Windows 11 24H2 and Windows Server 23H2 or 2025 allows remote attackers to elevate privileges. Microsoft has not published the authentication operation that mishandles untrusted input or the resulting privilege level. Exploitation requires network access and no credentials or user interaction; the elevated privilege level and concrete post-authentication actions remain unspecified.
The record
- CVE
- CVE-2025-21311
- Published
- Jan 14, 2025
- Updated
- Jun 9, 2026
- Vendor
- Microsoft
- Product
- Windows Server 2025 (Server Core installation)
- Classifications
- CWE-303
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jan 14, 2025CVE publishedPublication date reported by the CVE source.
- Jun 9, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=10.0.26100.0 <10.0.26100.2894
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
No public exploit references are available in this record.
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Technologies
Your stack
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Your stack
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