CVE-2025-21357
Microsoft Office Long Term Servicing Channel 2021 … 2024
Raw vector
CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:U/C:H/I:H/A:HSummary
CVE-2025-21357 is a medium-severity Use of Uninitialized Resource (CWE-908) vulnerability in Microsoft Office Long Term Servicing Channel. Its CVSS base score is 6.7 (Medium).
Operationally, exploitation aligns with the MITRE ATT&CK technique OS Credential Dumping (T1003); ranked at the 44th percentile by exploit likelihood (below the median); 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.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2025-2420
Vulnerability Data
Microsoft Outlook Remote Code Execution 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 (including static analysis) can find uses of uninitialized resources after they are coded.
Requiring documented development standards and tools can mandate initialization checks and safe patterns that stop the weakness from being introduced.
Engineering principles can require explicit resource initialization before use, structurally avoiding uninitialized access.
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 activities such as static analysis and code review directly prevent use of uninitialized resources while also addressing many other weaknesses.
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.
Security testing in development and acceptance can detect uninitialized resource usage through dynamic analysis and fuzzing.
Secure development life cycle mandates initialization checks and static analysis that can catch uninitialized resource use.
Application security requirements can specify mandatory initialization of variables and resources before use.
Secure system architecture and engineering principles include defensive coding practices that prevent use of uninitialized memory or objects.
Secure coding standards directly require explicit initialization of all variables and resources, substantially mitigating CWE-908.