Improper input validation in Microsoft Windows_10_1607
CVE-2026-20856
Improper input validation in Windows Server Update Service allows an unauthorized attacker to execute code over a network.
Vulnerability class: Drupalgeddon 2 (CVE-2018-7600)
EPSS: 0.011 (60.8th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 8.1 (High). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H.
Affected products
- Microsoft Windows_10_1607
- Microsoft Windows_10_1809
- Microsoft Windows_10_21h2
- Microsoft Windows_10_22h2
- Microsoft Windows 10 Version 1607 — versions 10.0.14393.0
- Microsoft Windows 10 Version 1809 — versions 10.0.17763.0
- Microsoft Windows 10 Version 21h2 — versions 10.0.19044.0
- Microsoft Windows 10 Version 22h2 — versions 10.0.19045.0
- Microsoft Windows_11_23h2
- Microsoft Windows_11_24h2
Weakness classification (CWE)
References
- secure@microsoft.com (vendor-advisory, patch, Vendor Advisory)
Frequently asked questions
- What is CVE-2026-20856?
- CVE-2026-20856 is a high-severity vulnerability in Microsoft Windows_10_1607, classified under Improper Input Validation. CVSS score: 8.1/10. Published 2026-01-13.
- How severe is CVE-2026-20856?
- High severity. CVSS v3 base score is 8.1 out of 10.