{"id":"CVE-2021-40456","aliases":["EUVD-2021-27633","GHSA-j5xg-6v4g-89vw"],"status":"published","title":"Windows AD FS Security Feature Bypass Vulnerability","description":"Windows AD FS Security Feature Bypass Vulnerability","severity":{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N/E:U/RL:O/RC:C","level":"medium","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-11","score":0.02341,"percentile":0.83845,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":false},"cwes":["CWE-863"],"published":"2021-10-13T00:26:54Z","modified":"2026-06-17T04:06:57Z","products":[{"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 version 2004"},{"vendor":"microsoft","product":"windows server version 20h2"},{"vendor":"microsoft","product":"windows_server"},{"vendor":"microsoft","product":"windows_server_2019"},{"vendor":"microsoft","product":"windows_server_2022"}],"references":[{"url":"https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-40456","tags":["x_refsource_MISC","x_transferred","Patch","Vendor Advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2021-40456"},{"url":"https://github.com/advisories/GHSA-j5xg-6v4g-89vw"}],"sources":{"cve":[{"id":"CVE-2021-40456","title":"Windows AD FS Security Feature Bypass Vulnerability","description":"Windows AD FS Security Feature Bypass Vulnerability","status":"published","published":"2021-10-13T00:26:54Z","modified":"2024-08-04T02:44:10.731Z","cvss":[{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N/E:U/RL:O/RC:C","level":"medium","assessor":"cna"}],"cwes":["CWE-863"],"updated_at":"2026-11-02T14:33:01.495293Z"}],"euvd":[{"id":"EUVD-2021-27633","description":"Windows AD FS Security Feature Bypass Vulnerability","status":"published","published":"2021-10-13T00:26:54Z","modified":"2024-08-04T02:44:10Z","cvss":[{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N/E:U/RL:O/RC:C","level":"medium"}],"updated_at":"2026-11-03T03:24:20.862157Z"}],"ghsa":[{"id":"GHSA-j5xg-6v4g-89vw","title":"Windows AD FS Security Feature Bypass Vulnerability","description":"Windows AD FS Security Feature Bypass Vulnerability","status":"published","published":"2022-05-24T19:17:33Z","modified":"2024-08-01T15:31:16Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N","level":"high"}],"cwes":["CWE-863"],"updated_at":"2026-11-02T14:57:46.205602Z"}],"nvd":[{"id":"CVE-2021-40456","description":"Windows AD FS Security Feature Bypass Vulnerability","status":"published","published":"2021-10-13T01:15:09.89Z","modified":"2026-06-17T04:06:57.37Z","cvss":[{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N","level":"medium","assessor":"secondary"},{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N","level":"high","assessor":"secondary"},{"version":"2.0","score":5,"vector":"AV:N/AC:L/Au:N/C:P/I:N/A:N","level":"medium","assessor":"primary"}],"cwes":["CWE-863"],"updated_at":"2026-11-02T14:06:59.689345Z"}]}}