CVE-2025-21333
Memory Safety in Microsoft Windows 10 21H2 ≤ 10.0.19044.5371
Raw vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:HSummary
CVE-2025-21333 is a high-severity Heap-based Buffer Overflow (CWE-122) vulnerability in Microsoft Windows 10 21H2. 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 5% of CVEs by exploit likelihood; CISA has added it to the Known Exploited Vulnerabilities catalog; a public proof-of-concept is referenced.
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-2025-21333 is an elevation of privilege vulnerability in the Windows Hyper-V NT Kernel Integration VSP component. It carries a CVSS 3.1 score of 7.8 and is associated with CWE-122, indicating a local attack vector that requires low privileges and no user interaction to achieve full compromise of confidentiality, integrity, and availability on affected systems.
An attacker with local access and limited privileges can exploit the flaw to escalate rights within the Hyper-V environment, potentially gaining control over kernel-level integration services and the underlying host.
Microsoft's advisory at msrc.microsoft.com provides official guidance and patches, while CISA has added the CVE to its Known Exploited Vulnerabilities catalog. Public resources from Vicarius include both detection and mitigation scripts, and Exploit-DB lists a corresponding proof-of-concept.
The vulnerability shows a high EPSS score with a current value of 0.7921 and a peak of 0.8228, consistent with documented real-world exploitation activity.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2025-2398
Vulnerability Data
Windows Hyper-V NT Kernel Integration VSP Elevation of Privilege Vulnerability
- CWE(s)
- KEV Date Added
- 14 January 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.