{"id":"CVE-2026-83991","aliases":["EUVD-2026-73359","GHSA-6xxg-24pf-j6jx"],"status":"published","title":"Windows Cloud Files Mini Filter Driver Tampering Vulnerability","description":"Missing authentication for critical function in Windows Cloud Files Mini Filter Driver allows an authorized attacker to perform tampering locally.","severity":{"version":"3.1","score":5.5,"vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N/E:U/RL:O/RC:C","level":"medium","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-11","score":0.00302,"percentile":0.2323,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":true,"fix_available":false},"cwes":["CWE-306"],"published":"2026-09-08T17:14:16Z","modified":"2026-10-31T16:12:59Z","exploits":[{"source":"pocgithub","id":"karollooool/CVE-2026-83991-writeup-and-poc","title":"karollooool/CVE-2026-83991-writeup-and-poc","date":"2026-09-09","url":"https://github.com/karollooool/CVE-2026-83991-writeup-and-poc"}],"products":[{"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 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_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_2019"},{"vendor":"microsoft","product":"windows_server_2022"},{"vendor":"microsoft","product":"windows_server_2025"}],"references":[{"url":"https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-83991","tags":["vendor-advisory","patch","Vendor Advisory","Patch"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-83991"},{"url":"https://github.com/advisories/GHSA-6xxg-24pf-j6jx"}],"sources":{"cve":[{"id":"CVE-2026-83991","title":"Windows Cloud Files Mini Filter Driver Tampering Vulnerability","description":"Missing authentication for critical function in Windows Cloud Files Mini Filter Driver allows an authorized attacker to perform tampering locally.","status":"published","published":"2026-09-08T17:14:16.048Z","modified":"2026-11-10T21:33:03.44Z","cvss":[{"version":"3.1","score":5.5,"vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N/E:U/RL:O/RC:C","level":"medium","assessor":"cna"}],"cwes":["CWE-306"],"updated_at":"2026-11-10T22:48:54.14451Z"}],"euvd":[{"id":"EUVD-2026-73359","description":"Missing authentication for critical function in Windows Cloud Files Mini Filter Driver allows an authorized attacker to perform tampering locally.","status":"published","published":"2026-09-08T17:14:16Z","modified":"2026-11-10T21:33:03Z","cvss":[{"version":"3.1","score":5.5,"vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N/E:U/RL:O/RC:C","level":"medium"}],"updated_at":"2026-11-10T22:23:50.104128Z"}],"ghsa":[{"id":"GHSA-6xxg-24pf-j6jx","title":"Missing authentication for critical function in Windows Cloud Files Mini Filter Driver allows an...","description":"Missing authentication for critical function in Windows Cloud Files Mini Filter Driver allows an authorized attacker to perform tampering locally.","status":"published","published":"2026-09-08T18:33:38Z","modified":"2026-09-08T18:34:14Z","cvss":[{"version":"3.1","score":5.5,"vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N","level":"medium"}],"cwes":["CWE-306"],"updated_at":"2026-11-02T15:11:34.690977Z"}],"nvd":[{"id":"CVE-2026-83991","description":"Missing authentication for critical function in Windows Cloud Files Mini Filter Driver allows an authorized attacker to perform tampering locally.","status":"published","published":"2026-09-08T18:21:09.823Z","modified":"2026-09-09T20:14:54.747Z","cvss":[{"version":"3.1","score":5.5,"vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N","level":"medium","assessor":"secondary"}],"cwes":["CWE-306"],"updated_at":"2026-11-02T14:12:45.264578Z"}]}}