{"id":"CVE-2026-66799","aliases":["EUVD-2026-56450","GHSA-cr27-wq5j-8m89"],"status":"published","title":"Windows Key Guard Elevation of Privilege Vulnerability","description":"Heap-based buffer overflow in Windows Key Guard allows an authorized attacker to elevate privileges locally.","severity":{"version":"3.1","score":7.8,"vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C","level":"high","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-12","score":0.00333,"percentile":0.26982,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":false},"cwes":["CWE-122"],"published":"2026-08-11T17:05:06Z","modified":"2026-11-10T21:58:48Z","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 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 2012"},{"vendor":"microsoft","product":"windows server 2012 (server core installation)"},{"vendor":"microsoft","product":"windows server 2012 r2"},{"vendor":"microsoft","product":"windows server 2012 r2 (server core installation)"},{"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 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_11_26h1"},{"vendor":"microsoft","product":"windows_server_2012"},{"vendor":"microsoft","product":"windows_server_2016"},{"vendor":"microsoft","product":"windows_server_2019"},{"vendor":"microsoft","product":"windows_server_2022"},{"vendor":"microsoft","product":"windows_server_2025"}],"references":[{"url":"https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-66799","tags":["vendor-advisory","patch","Patch","Vendor Advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-66799"},{"url":"https://github.com/advisories/GHSA-cr27-wq5j-8m89"}],"sources":{"cve":[{"id":"CVE-2026-66799","title":"Windows Key Guard Elevation of Privilege Vulnerability","description":"Heap-based buffer overflow in Windows Key Guard allows an authorized attacker to elevate privileges locally.","status":"published","published":"2026-08-11T17:05:06.12Z","modified":"2026-11-10T21:58:48.942Z","cvss":[{"version":"3.1","score":7.8,"vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C","level":"high","assessor":"cna"}],"cwes":["CWE-122"],"updated_at":"2026-11-10T22:48:52.144232Z"}],"euvd":[{"id":"EUVD-2026-56450","description":"Heap-based buffer overflow in Windows Key Guard allows an authorized attacker to elevate privileges locally.","status":"published","published":"2026-08-11T17:05:06Z","modified":"2026-11-10T21:58:48Z","cvss":[{"version":"3.1","score":7.8,"vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C","level":"high"}],"updated_at":"2026-11-10T23:24:17.839385Z"}],"ghsa":[{"id":"GHSA-cr27-wq5j-8m89","title":"Heap-based buffer overflow in Windows Key Guard allows an authorized attacker to elevate...","description":"Heap-based buffer overflow in Windows Key Guard allows an authorized attacker to elevate privileges locally.","status":"published","published":"2026-08-11T18:31:41Z","modified":"2026-08-11T18:31:49Z","cvss":[{"version":"3.1","score":7.8,"vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","level":"high"}],"cwes":["CWE-122"],"updated_at":"2026-11-02T15:10:20.59674Z"}],"nvd":[{"id":"CVE-2026-66799","description":"Heap-based buffer overflow in Windows Key Guard allows an authorized attacker to elevate privileges locally.","status":"published","published":"2026-08-11T17:19:01.4Z","modified":"2026-08-16T19:17:21.4Z","cvss":[{"version":"3.1","score":7.8,"vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","level":"high","assessor":"secondary"}],"cwes":["CWE-122"],"updated_at":"2026-11-02T14:12:36.880938Z"}]}}