{"id":"CVE-2026-21255","aliases":["EUVD-2026-7328","GHSA-r2rm-869g-w2g5"],"status":"published","title":"Windows Hyper-V Security Feature Bypass Vulnerability","description":"Improper access control in Windows Hyper-V allows an authorized attacker to bypass a security feature locally.","severity":{"version":"3.1","score":8.8,"vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H/E:U/RL:O/RC:C","level":"high","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-12","score":0.00375,"percentile":0.31892,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":false},"cwes":["CWE-284"],"published":"2026-02-10T17:51:38Z","modified":"2026-08-19T16:26:08Z","products":[{"vendor":"microsoft","product":"windows 10 version 1607"},{"vendor":"microsoft","product":"windows 10 version 1809"},{"vendor":"microsoft","product":"windows 10 version 21h2"},{"vendor":"microsoft","product":"windows 10 version 22h2"},{"vendor":"microsoft","product":"windows 11 version 22h3"},{"vendor":"microsoft","product":"windows 11 version 23h2"},{"vendor":"microsoft","product":"windows 11 version 24h2"},{"vendor":"microsoft","product":"windows 11 version 25h2"},{"vendor":"microsoft","product":"windows 11 version 26h1"},{"vendor":"microsoft","product":"windows server 2016"},{"vendor":"microsoft","product":"windows server 2016 (server core installation)"},{"vendor":"microsoft","product":"windows server 2019"},{"vendor":"microsoft","product":"windows server 2019 (server core installation)"},{"vendor":"microsoft","product":"windows server 2022"},{"vendor":"microsoft","product":"windows server 2022, 23h2 edition (server core installation)"},{"vendor":"microsoft","product":"windows server 2025"},{"vendor":"microsoft","product":"windows server 2025 (server core installation)"},{"vendor":"microsoft","product":"windows_10_1607"},{"vendor":"microsoft","product":"windows_10_1809"},{"vendor":"microsoft","product":"windows_10_21h2"},{"vendor":"microsoft","product":"windows_10_22h2"},{"vendor":"microsoft","product":"windows_11_23h2"},{"vendor":"microsoft","product":"windows_11_24h2"},{"vendor":"microsoft","product":"windows_11_25h2"},{"vendor":"microsoft","product":"windows_server_2016"},{"vendor":"microsoft","product":"windows_server_2019"},{"vendor":"microsoft","product":"windows_server_2022"},{"vendor":"microsoft","product":"windows_server_2022_23h2"},{"vendor":"microsoft","product":"windows_server_2025"}],"references":[{"url":"https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21255","tags":["vendor-advisory","patch","Vendor Advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-21255"},{"url":"https://github.com/advisories/GHSA-r2rm-869g-w2g5"}],"sources":{"cve":[{"id":"CVE-2026-21255","title":"Windows Hyper-V Security Feature Bypass Vulnerability","description":"Improper access control in Windows Hyper-V allows an authorized attacker to bypass a security feature locally.","status":"published","published":"2026-02-10T17:51:38.926Z","modified":"2026-08-19T16:26:08.911Z","cvss":[{"version":"3.1","score":8.8,"vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H/E:U/RL:O/RC:C","level":"high","assessor":"cna"}],"cwes":["CWE-284"],"updated_at":"2026-11-02T13:41:42.05254Z"}],"euvd":[{"id":"EUVD-2026-7328","description":"Improper access control in Windows Hyper-V allows an authorized attacker to bypass a security feature locally.","status":"published","published":"2026-02-10T17:51:38Z","modified":"2026-08-19T16:26:08Z","cvss":[{"version":"3.1","score":8.8,"vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H/E:U/RL:O/RC:C","level":"high"}],"updated_at":"2026-11-02T18:01:44.172516Z"}],"ghsa":[{"id":"GHSA-r2rm-869g-w2g5","title":"Improper access control in Windows Hyper-V allows an authorized attacker to bypass a security...","description":"Improper access control in Windows Hyper-V allows an authorized attacker to bypass a security feature locally.","status":"published","published":"2026-02-10T18:30:41Z","modified":"2026-02-10T18:30:50Z","cvss":[{"version":"3.1","score":8.8,"vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H","level":"high"}],"cwes":["CWE-284"],"updated_at":"2026-11-02T15:06:07.875228Z"}],"nvd":[{"id":"CVE-2026-21255","description":"Improper access control in Windows Hyper-V allows an authorized attacker to bypass a security feature locally.","status":"published","published":"2026-02-10T18:16:27.167Z","modified":"2026-06-17T10:18:22.39Z","cvss":[{"version":"3.1","score":8.8,"vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H","level":"high","assessor":"secondary"}],"cwes":["CWE-284"],"updated_at":"2026-11-02T14:12:05.52517Z"}]}}