CVE-2025-21418
Memory Safety in Microsoft Windows 10 1607 ≤ 10.0.10240.20915
Raw vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:HSummary
CVE-2025-21418 is a high-severity Heap-based Buffer Overflow (CWE-122) vulnerability in Microsoft Windows 10 1607. Its CVSS base score is 7.8 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Privilege Escalation (T1068); ranked in the top 27% of CVEs by exploit likelihood; CISA has added it to the Known Exploited Vulnerabilities catalog.
The strongest mitigations our analysis identified map to SA-11 (Developer Testing and Evaluation) and SI-10 (Information Input Validation) — 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.
CVE-2025-21418 is an elevation-of-privilege vulnerability in the Windows Ancillary Function Driver for WinSock. It carries a CVSS 3.1 base score of 7.8 and is associated with CWE-122, indicating a heap-based buffer overflow that allows an attacker to execute arbitrary code with elevated privileges on an affected Windows system.
A local attacker with low privileges can exploit the flaw without user interaction to obtain full control over the target host, achieving high impact on confidentiality, integrity, and availability. The vulnerability is reachable from standard user contexts, enabling privilege escalation on multi-user or shared Windows systems.
Microsoft’s security advisory at msrc.microsoft.com details the affected Windows versions and provides patches that remediate the issue; organizations should apply the updates promptly. CISA has added CVE-2025-21418 to its Known Exploited Vulnerabilities catalog, confirming observed in-the-wild exploitation.
EPSS for the CVE reached a peak of 0.1358 before settling at the current value of 0.1029, indicating measurable post-disclosure exploitation interest.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2025-2476
Vulnerability Data
Windows Ancillary Function Driver for WinSock Elevation of Privilege Vulnerability
- CWE(s)
- KEV Date Added
- 11 February 2025
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
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V1.4.1
Mitigating Controls (NIST 800-53 r5) AI
Developer testing and evaluation (including fuzzing and memory-error detectors) can discover heap overflows after they have been coded.
Input validation enforces bounds checking on data written to heap buffers, directly stopping the overflow condition from being introduced.
Security engineering principles require use of memory-safe constructs and bounds-checked allocation routines that avoid introducing heap overflows.
Memory-protection mechanisms limit the ability of a heap overflow to execute attacker-controlled code or corrupt adjacent structures.
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-development practices directly require bounds checking and safe memory handling that prevent heap overflows.
Vulnerability scanning and recording can discover heap-overflow flaws but does not prevent their introduction in code.
Timely patching removes known heap-overflow instances after they exist.
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 heap overflows before release.
Secure development lifecycle mandates practices that reduce the likelihood of introducing heap overflows.
Application security requirements can specify bounds-checking and safe memory APIs that mitigate heap overflows.
Secure architecture and engineering principles include memory-safety and input-validation controls that address heap overflows.
Secure coding standards directly prescribe techniques (safe functions, bounds checks) that prevent heap-based buffer overflows.
Change management ensures controlled deployment of fixes for discovered heap-overflow vulnerabilities.