{"id":"CVE-2021-31961","title":"Windows InstallService Elevation of Privilege Vulnerability","summary":"Windows InstallService Elevation of Privilege Vulnerability","severity":"medium","cvss":6.1,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:H","cwe":["CWE-269"],"vendor":"microsoft","product":"windows_10","affected":["windows_10 = 20h2","windows_10 = 21h1","windows_10 = 1809","windows_10 = 1909","windows_10 = 2004","windows_server_2016 = 20h2","windows_server_2016 = 2004","windows_server_2019"],"published":"2021-07-14","updated":"2026-08-10","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2021-31961","references":[{"url":"https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-31961","label":"secure@microsoft.com"},{"url":"https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-31961","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://www.zerodayinitiative.com/advisories/ZDI-21-818/","label":"af854a3a-2127-422b-91ae-364da2661108"}],"tags":["nvd"],"epss":0.00801,"epssPercentile":0.5471,"zeroDay":true,"ingestedAt":"2026-08-10T16:41:14.440Z","slug":"CVE-2021-31961","body":"## Overview\n\nWindows InstallService Elevation of Privilege Vulnerability\n\n## Affected\n\n- `windows_10 = 20h2`\n- `windows_10 = 21h1`\n- `windows_10 = 1809`\n- `windows_10 = 1909`\n- `windows_10 = 2004`\n- `windows_server_2016 = 20h2`\n- `windows_server_2016 = 2004`\n- `windows_server_2019`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"midnight","depthScore":59,"depthScoreParts":{"impact":33.6,"likelihood":0.2,"exploitation":25,"ransomware":0},"changes":[]}