{"id":"CVE-2026-20872","title":"External control of file name or path in Windows NTLM allows an unauthorized attacker to perform spoofing over a network.","summary":"External control of file name or path in Windows NTLM allows an unauthorized attacker to perform spoofing over a network.","severity":"medium","cvss":6.5,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N","cwe":["CWE-73"],"vendor":"microsoft","product":"windows_10_1607","affected":["windows_10_1607 < 10.0.14393.8783","windows_10_1809 < 10.0.17763.8276","windows_10_21h2 < 10.0.19044.6809","windows_10_22h2 < 10.0.19045.6809","windows_11_23h2 < 10.0.22631.6491","windows_11_24h2 < 10.0.26100.7623","windows_11_25h2 < 10.0.26200.7623","windows_server_2008","windows_server_2008 = r2","windows_server_2012","windows_server_2012 = r2","windows_server_2016 < 10.0.14393.8783","windows_server_2019 < 10.0.17763.8276","windows_server_2022 < 10.0.20348.4648","windows_server_2022_23h2 < 10.0.25398.2092","windows_server_2025 < 10.0.26100.32230"],"patched":["windows_10_1607 10.0.14393.8783","windows_10_1809 10.0.17763.8276","windows_10_21h2 10.0.19044.6809","windows_10_22h2 10.0.19045.6809","windows_11_23h2 10.0.22631.6491","windows_11_24h2 10.0.26100.7623","windows_11_25h2 10.0.26200.7623","windows_server_2016 10.0.14393.8783","windows_server_2019 10.0.17763.8276","windows_server_2022 10.0.20348.4648","windows_server_2022_23h2 10.0.25398.2092","windows_server_2025 10.0.26100.32230"],"published":"2026-01-13","updated":"2026-07-30","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-20872","references":[{"url":"https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-20872","label":"secure@microsoft.com"},{"url":"https://www.vicarius.io/vsociety/posts/cve-2026-20872-detection-script-spoofing-vulnerability-in-windows-ntlm","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://www.vicarius.io/vsociety/posts/cve-2026-20872-mitigation-script-spoofing-vulnerability-in-windows-ntlm","label":"af854a3a-2127-422b-91ae-364da2661108"}],"tags":["nvd"],"epss":0.20059,"epssPercentile":0.97379,"ingestedAt":"2026-07-31T06:58:52.869Z","slug":"CVE-2026-20872","body":"## Overview\n\nExternal control of file name or path in Windows NTLM allows an unauthorized attacker to perform spoofing over a network.\n\n## Affected\n\n- `windows_10_1607 < 10.0.14393.8783`\n- `windows_10_1809 < 10.0.17763.8276`\n- `windows_10_21h2 < 10.0.19044.6809`\n- `windows_10_22h2 < 10.0.19045.6809`\n- `windows_11_23h2 < 10.0.22631.6491`\n- `windows_11_24h2 < 10.0.26100.7623`\n- `windows_11_25h2 < 10.0.26200.7623`\n- `windows_server_2008`\n- `windows_server_2008 = r2`\n- `windows_server_2012`\n- `windows_server_2012 = r2`\n- `windows_server_2016 < 10.0.14393.8783`\n- `windows_server_2019 < 10.0.17763.8276`\n- `windows_server_2022 < 10.0.20348.4648`\n- `windows_server_2022_23h2 < 10.0.25398.2092`\n- `windows_server_2025 < 10.0.26100.32230`\n\n## Remediation\n\nUpgrade past the affected range:\n\n- `windows_10_1607 10.0.14393.8783`\n- `windows_10_1809 10.0.17763.8276`\n- `windows_10_21h2 10.0.19044.6809`\n- `windows_10_22h2 10.0.19045.6809`\n- `windows_11_23h2 10.0.22631.6491`\n- `windows_11_24h2 10.0.26100.7623`\n- `windows_11_25h2 10.0.26200.7623`\n- `windows_server_2016 10.0.14393.8783`\n- `windows_server_2019 10.0.17763.8276`\n- `windows_server_2022 10.0.20348.4648`\n- `windows_server_2022_23h2 10.0.25398.2092`\n- `windows_server_2025 10.0.26100.32230`","depth":"sunlit","depthScore":40,"depthScoreParts":{"impact":35.8,"likelihood":4,"exploitation":0,"ransomware":0},"changes":[]}