{"id":"CVE-2026-83674","aliases":["EUVD-2026-99618","GHSA-f3fh-9v4g-62gx"],"status":"published","title":"Active Directory Federation Services (AD FS) Spoofing Vulnerability","description":"Weak authentication in Active Directory Federation Services (AD FS) allows an unauthorized attacker to perform spoofing over a network.","severity":{"version":"3.1","score":8.1,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C","level":"high","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-11","score":0.00713,"percentile":0.54056,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":false},"cwes":["CWE-1390"],"published":"2026-10-13T19:00:14Z","modified":"2026-11-10T20:38:53Z","products":[{"vendor":"microsoft","product":"windows 10 version 1607"},{"vendor":"microsoft","product":"windows 10 version 1809"},{"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_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-2026-83674","tags":["vendor-advisory","patch","Vendor Advisory","Patch"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-83674"},{"url":"https://github.com/advisories/GHSA-f3fh-9v4g-62gx"}],"sources":{"cve":[{"id":"CVE-2026-83674","title":"Active Directory Federation Services (AD FS) Spoofing Vulnerability","description":"Weak authentication in Active Directory Federation Services (AD FS) allows an unauthorized attacker to perform spoofing over a network.","status":"published","published":"2026-10-13T19:00:14.284Z","modified":"2026-11-10T20:38:53.921Z","cvss":[{"version":"3.1","score":8.1,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C","level":"high","assessor":"cna"}],"cwes":["CWE-1390"],"updated_at":"2026-11-10T22:18:28.707469Z"}],"euvd":[{"id":"EUVD-2026-99618","description":"Weak authentication in Active Directory Federation Services (AD FS) allows an unauthorized attacker to perform spoofing over a network.","status":"published","published":"2026-10-13T19:00:14Z","modified":"2026-11-10T20:38:53Z","cvss":[{"version":"3.1","score":8.1,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C","level":"high"}],"updated_at":"2026-11-10T22:23:59.503929Z"}],"ghsa":[{"id":"GHSA-f3fh-9v4g-62gx","title":"Weak authentication in Active Directory Federation Services (AD FS) allows an unauthorized...","description":"Weak authentication in Active Directory Federation Services (AD FS) allows an unauthorized attacker to perform spoofing over a network.","status":"published","published":"2026-10-13T21:34:36Z","modified":"2026-10-13T21:34:36Z","cvss":[{"version":"3.1","score":8.1,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H","level":"high"}],"cwes":["CWE-1390"],"updated_at":"2026-11-02T15:13:16.244853Z"}],"nvd":[{"id":"CVE-2026-83674","description":"Weak authentication in Active Directory Federation Services (AD FS) allows an unauthorized attacker to perform spoofing over a network.","status":"published","published":"2026-10-13T19:20:09.393Z","modified":"2026-10-29T20:51:14.063Z","cvss":[{"version":"3.1","score":8.1,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H","level":"high","assessor":"secondary"}],"cwes":["CWE-1390"],"updated_at":"2026-11-02T14:12:57.603498Z"}]}}