CVE-2026-21244
Published: 10 February 2026
Summary
CVE-2026-21244 is a high-severity Heap-based Buffer Overflow (CWE-122) vulnerability in Microsoft Windows 11 23H2. Its CVSS base score is 7.3 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Privilege Escalation (T1068); ranked in the top 39.9% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog.
Threat & Defense at a Glance
Threat & Defense Details
Likely Mitigating ControlsAI
Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.
Out-of-bounds writes that corrupt control flow or inject shellcode are rendered non-executable by the same memory protections.
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Heap buffer overflow in Hyper-V hypervisor directly enables local privilege escalation via arbitrary code execution in the hypervisor process context.
NVD Description
Heap-based buffer overflow in Windows Hyper-V allows an authorized attacker to execute code locally.
Deeper analysisAI
CVE-2026-21244 is a heap-based buffer overflow vulnerability (CWE-122, CWE-787) in the Windows Hyper-V hypervisor. Published on 2026-02-10, it has a CVSS v3.1 base score of 7.3 (AV:L/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:H) and affects Windows systems utilizing the Hyper-V component for virtualization.
The vulnerability can be exploited by an authorized local attacker with low privileges who requires user interaction to trigger it. Successful exploitation enables arbitrary code execution in the context of the Hyper-V process, granting high-impact access to confidentiality, integrity, and availability.
Mitigation details, including available patches, are provided in the Microsoft Security Response Center advisory at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21244.
Details
- CWE(s)