CVE-2026-20856

high

Description

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

References

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-20856

Details

Source: Mitre, NVD

Published: 2026-01-13

Updated: 2026-01-15

Risk Information

CVSS v2

Base Score: 7.6

Vector: CVSS2#AV:N/AC:H/Au:N/C:C/I:C/A:C

Severity: High

CVSS v3

Base Score: 8.1

Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

Severity: High

EPSS

EPSS: 0.00115