A remote code execution vulnerability exists when Windows Hyper-V on a host server fails to properly validate input from an authenticated user on a guest operating system. To exploit the vulnerability, an attacker could run a specially crafted application on a guest operating system that could cause the Hyper-V host operating system to execute arbitrary code.
\nAn attacker who successfully exploited the vulnerability could execute arbitrary code on the host operating system.
\nThe security update addresses the vulnerability by correcting how Hyper-V validates guest operating system user input.
","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H","score":8.8},"cwes":["CWE-20"],"references":["https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2020-16891","https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2020-16891"],"products":["microsoft:windows_10","microsoft:windows_7","microsoft:windows_8.1","microsoft:windows_server_2008","microsoft:windows_server_2012","microsoft:windows_server_2016","microsoft:windows_server_2019"],"source":"nvd","synced_at":"2026-10-19T21:09:53.489947993+00:00"},"epss":{"cve":"CVE-2020-16891","score":0.00945,"percentile":0.61082,"date":"2026-11-01"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}