{"id":"CVE-2026-84009","aliases":["EUVD-2026-99446","GHSA-3hrm-g38h-q887"],"status":"published","title":"Windows Projected File System Tampering Vulnerability","description":"Time-of-check time-of-use (toctou) race condition in Windows Projected File System allows an authorized attacker to perform tampering locally.","severity":{"version":"3.1","score":4.7,"vector":"CVSS:3.1/AV:L/AC:H/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":0.00197,"percentile":0.09507,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":false},"cwes":["CWE-367"],"published":"2026-10-13T18:59:59Z","modified":"2026-11-10T20:37:15Z","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 11 version 26h2"},{"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_11_26h2"},{"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-2026-84009","tags":["vendor-advisory","patch","Vendor Advisory","Patch"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-84009"},{"url":"https://github.com/advisories/GHSA-3hrm-g38h-q887"}],"sources":{"cve":[{"id":"CVE-2026-84009","title":"Windows Projected File System Tampering Vulnerability","description":"Time-of-check time-of-use (toctou) race condition in Windows Projected File System allows an authorized attacker to perform tampering locally.","status":"published","published":"2026-10-13T18:59:59.473Z","modified":"2026-11-10T20:37:15.165Z","cvss":[{"version":"3.1","score":4.7,"vector":"CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:N/E:U/RL:O/RC:C","level":"medium","assessor":"cna"}],"cwes":["CWE-367"],"updated_at":"2026-11-10T22:18:29.471829Z"}],"euvd":[{"id":"EUVD-2026-99446","description":"Time-of-check time-of-use (toctou) race condition in Windows Projected File System allows an authorized attacker to perform tampering locally.","status":"published","published":"2026-10-13T18:59:59Z","modified":"2026-11-10T20:37:15Z","cvss":[{"version":"3.1","score":4.7,"vector":"CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:N/E:U/RL:O/RC:C","level":"medium"}],"updated_at":"2026-11-10T21:23:21.470164Z"}],"ghsa":[{"id":"GHSA-3hrm-g38h-q887","title":"Time-of-check time-of-use (toctou) race condition in Windows Projected File System allows an...","description":"Time-of-check time-of-use (toctou) race condition in Windows Projected File System allows an authorized attacker to perform tampering locally.","status":"published","published":"2026-10-13T21:35:15Z","modified":"2026-10-13T21:35:21Z","cvss":[{"version":"3.1","score":4.7,"vector":"CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:N","level":"medium"}],"cwes":["CWE-367"],"updated_at":"2026-11-02T15:13:17.40783Z"}],"nvd":[{"id":"CVE-2026-84009","description":"Time-of-check time-of-use (toctou) race condition in Windows Projected File System allows an authorized attacker to perform tampering locally.","status":"published","published":"2026-10-13T19:20:50.927Z","modified":"2026-10-19T19:16:10.873Z","cvss":[{"version":"3.1","score":4.7,"vector":"CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:N","level":"medium","assessor":"secondary"}],"cwes":["CWE-367"],"updated_at":"2026-11-02T14:12:58.13117Z"}]}}