CVE-2026-40399
Published: 12 May 2026
Summary
CVE-2026-40399 is a high-severity Stack-based Buffer Overflow (CWE-121) 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 15.7th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-29661
Vulnerability details
Concurrent execution using shared resource with improper synchronization ('race condition') in Windows TCP/IP allows an authorized attacker to elevate privileges locally.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Stack-based buffer overflow enables local privilege escalation by an authorized attacker, directly mapping to T1068 Exploitation for Privilege Escalation.
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Affected Assets
Mitigating Controls
No mitigating controls mapped yet. The per-CVE control annotator has not reached this CVE.