CVE-2026-26156
Published: 14 April 2026
Summary
CVE-2026-26156 is a high-severity Improper Input Validation (CWE-20) vulnerability in Microsoft Windows 11 23H2. 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 34.4th 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-10 (Information Input Validation) and SI-16 (Memory Protection).
Deeper analysis
CVE-2026-26156 is a heap-based buffer overflow vulnerability in Windows Hyper-V. Published on 2026-04-14T18:16:47.810, it carries a CVSS v3.1 base score of 7.8 (AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H) and is linked to CWE-20 (Improper Input Validation), CWE-122 (Heap-based Buffer Overflow), and CWE-125 (Out-of-bounds Read).
The vulnerability allows an unauthorized attacker with local access to execute code locally by leveraging low attack complexity and tricking a user into some interaction. Successful exploitation results in high impacts to confidentiality, integrity, and availability.
Microsoft's Security Response Center provides an update guide with details on mitigation and patching at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-26156.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-22380
Vulnerability details
Heap-based buffer overflow in Windows Hyper-V allows an unauthorized attacker to execute code locally.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Heap-based buffer overflow in Hyper-V with local AV, no privileges required, and user interaction directly enables local code execution for privilege escalation (T1068).
CVEs Like This One
Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
Requires timely patching of the heap-based buffer overflow vulnerability in Windows Hyper-V as detailed in Microsoft's update guide, directly preventing exploitation.
Implements memory safeguards such as DEP and ASLR to protect against heap-based buffer overflows (CWE-122) and unauthorized local code execution in Hyper-V.
Enforces proper input validation in Hyper-V to address improper input handling (CWE-20) that leads to the buffer overflow and out-of-bounds read (CWE-125).