CVE-2026-20856

moderate-risk
Published 2026-01-13

Improper input validation in Windows Server Update Service allows an unauthorized attacker to execute code over a network.

Do I need to act?

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0.13% chance of exploitation
EPSS score — low exploit probability
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Not on CISA KEV list
No confirmed active exploitation reported to CISA
?
Patch status unknown
Check vendor advisories for fix availability and mitigation guidance
8
CVSS 8.1/10 High
NETWORK / HIGH complexity

Affected Vendors

43
/ 100
moderate-risk
Severity 24/34 · High
Exploitability 1/34 · Minimal
Exposure 18/34 · Moderate