Buffer overflow in Microsoft Windows 11 23h2
CVE-2026-45657
Use after free in Windows Kernel allows an unauthorized attacker to execute code over a network.
Vulnerability class: Buffer Overflow
Published · last modified .
CVSS v3 metric
CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.
EPSS exploit prediction
EPSS: 0.010 (60.7th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 61st percentile — 60.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.155 · newest: 0.010 · change: -0.145
Affected products
- Microsoft Windows 11 23h2
- Microsoft Windows 11 24h2
- Microsoft Windows 11 25h2
- Microsoft Windows 11 26h1
- Microsoft Windows 11 Version 23h2 — versions 10.0.22631.0
- Microsoft Windows 11 Version 24h2 — versions 10.0.26100.0
- Microsoft Windows 11 Version 25h2 — versions 10.0.26200.0
- Microsoft Windows 11 Version 26h1 — versions 10.0.28000.0
- Microsoft Windows Server 2022 — versions 10.0.20348.0
- Microsoft Windows Server 2022
Weakness classification (CWE)
References
- Windows Kernel Remote Code Execution Vulnerability (vendor-advisory, patch, Vendor Advisory)
Frequently asked questions
- What is CVE-2026-45657?
- CVE-2026-45657 is a critical-severity vulnerability in Microsoft Windows 11 23h2, classified under Heap-based Buffer Overflow. CVSS score: 9.8/10. Published 2026-06-09.
- How severe is CVE-2026-45657?
- Critical severity. CVSS v3 base score is 9.8 out of 10.