Raw vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HSummary
CVE-2025-21311 is a critical-severity Incorrect Implementation of Authentication Algorithm (CWE-303) vulnerability in Microsoft Windows 11 24H2. Its CVSS base score is 9.8 (Critical).
Operationally, exploitation aligns with the MITRE ATT&CK technique External Remote Services (T1133); ranked in the top 19% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified map to SA-11 (Developer Testing and Evaluation) and SA-15 (Development Process, Standards, and Tools) — see the control section below for these in your framework.
Deeper analysis AI-assisted summary
Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.
Windows NTLM V1 Elevation of Privilege Vulnerability CVE-2025-21311 affects the Windows implementation of the NTLM version 1 authentication protocol. The flaw carries a CVSS 3.1 score of 9.8 and is associated with CWE-303, indicating an incorrect implementation of an authentication algorithm that can be reached over the network without credentials or user interaction.
An unauthenticated attacker can exploit the vulnerability remotely to obtain elevated privileges equivalent to those of a local administrator, resulting in full compromise of confidentiality, integrity, and availability on the target system.
Microsoft’s advisory at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-21311 addresses the issue and supplies the corresponding security update. The associated EPSS score rose from lower values to a peak of 0.0684 on 2026-02-03 before receding to its current level of 0.0442, indicating a temporary increase in observed exploitation interest after disclosure.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2025-2376
Vulnerability Data
Windows NTLM V1 Elevation of Privilege Vulnerability
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
Developer testing and evaluation at post-design stages directly uncovers incorrect implementations of required authentication algorithms.
Requiring documented development processes, standards, and tools reduces the chance that an established authentication algorithm is coded incorrectly.
Mitigating Controls (NIST CSF 2.0) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.
Secure SDLC practices directly require correct implementation of authentication algorithms.
Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.
Secure authentication control directly requires correct implementation of authentication algorithms.
Security testing can detect flawed authentication implementations but does not prevent them by itself.
Cryptography control addresses proper use of authentication algorithms but is broader than authentication alone.
Secure development lifecycle includes verification steps that can catch incorrect authentication implementations.
Application security requirements can specify correct authentication algorithm use but do not guarantee correct implementation.
Secure coding practices reduce the likelihood of incorrect authentication algorithm implementation.