PatchTheCVECVE-2026-40402: Use after free in Windows Hyper-V allows an unauthorized attacker to elevate privileges locally.
CVE-2026-40402 is a critical-severity flaw (CVSS 9.3) affecting windows 11 23h2, windows server 2022. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.
Use after free in Windows Hyper-V allows an unauthorized attacker to elevate privileges locally.
Why this priority
- Critical severity
- On your watchlist
A fixed release or distro patch exists.
Risk facts
| CVSS score | 9.3 (Critical) |
| Attack vector | Local |
| Attack complexity | Low |
| Privileges needed | None |
| User interaction | None |
| EPSS exploit chance | 0.3% (top 74%) |
| CISA exploited list | No |
| Weakness | CWE-416 |
| Published | 2026-05-12 |
| Last modified | 2026-06-17 |
Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score
Am I affected?
Timeline
- Published CVE record published
- Updated Record last modified
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.
Quick answers
How do I fix CVE-2026-40402?
windows 11 23h2: upgrade to 10.0.22631.7079; windows server 2022: upgrade to 10.0.20348.5074. Exact commands for each OS are on this page.
Is CVE-2026-40402 being exploited?
CVE-2026-40402 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.
What does CVE-2026-40402 affect?
CVE-2026-40402 affects windows 11 23h2, windows server 2022. Severity is critical (CVSS 9.3). Use after free in Windows Hyper-V allows an unauthorized attacker to elevate privileges locally.
How urgent is CVE-2026-40402?
Priority 44/100. Critical severity; On your watchlist
Software pages
Windows vulnerabilities · Windows Server vulnerabilities · Hyper-V vulnerabilities
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