CVE-2026-21246
Published: 10 February 2026
Summary
CVE-2026-21246 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 at the 8.7th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified are NIST 800-53 SI-16 (Memory Protection) and SI-2 (Flaw Remediation).
Threat & Defense at a Glance
Threat & Defense Details
Mitigating Controls (NIST 800-53 r5)AI
Requires identification, reporting, and timely correction of system flaws such as this heap-based buffer overflow via patching as provided by Microsoft.
Implements memory protection safeguards like address space randomization and non-executable memory that directly mitigate exploitation of heap-based buffer overflows.
Enforces least privilege for user accounts and processes, limiting the initial access and potential impact of local privilege escalation attempts.
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Heap buffer overflow in local graphics component directly enables local privilege escalation from low-privileged context.
NVD Description
Heap-based buffer overflow in Microsoft Graphics Component allows an authorized attacker to elevate privileges locally.
Deeper analysisAI
CVE-2026-21246 is a heap-based buffer overflow vulnerability in the Microsoft Graphics Component, published on 2026-02-10. It is associated with CWE-122 (Heap-based Buffer Overflow) and CWE-787 (Out-of-bounds Write), carrying a CVSS v3.1 base score of 7.8 (AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H). The flaw affects systems utilizing this graphics component, enabling local privilege escalation.
An authorized local attacker with low privileges can exploit this vulnerability due to its low attack complexity and lack of required user interaction. Successful exploitation grants high-impact access to confidentiality, integrity, and availability, allowing the attacker to elevate privileges on the affected system.
Microsoft's Security Response Center provides an update guide at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21246, detailing mitigation steps and available patches for remediation.
Details
- CWE(s)