{"id":"CVE-2026-20921","aliases":["EUVD-2026-2122","GHSA-rj95-xj64-7m2x"],"status":"published","title":"Windows SMB Server Elevation of Privilege Vulnerability","description":"Concurrent execution using shared resource with improper synchronization ('race condition') in Windows SMB Server allows an authorized attacker to elevate privileges over a network.","severity":{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C","level":"high","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-12","score":0.01176,"percentile":0.68018,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":false},"cwes":["CWE-362"],"published":"2026-01-13T17:56:39Z","modified":"2026-07-30T21:17:08Z","products":[{"vendor":"microsoft","product":"windows 10 version 1607"},{"vendor":"microsoft","product":"windows 10 version 1809"},{"vendor":"microsoft","product":"windows 10 version 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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 2022, 23h2 edition (server core installation)"},{"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_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_server_2008"},{"vendor":"microsoft","product":"windows_server_2012"},{"vendor":"microsoft","product":"windows_server_2016"},{"vendor":"microsoft","product":"windows_server_2019"},{"vendor":"microsoft","product":"windows_server_2022"},{"vendor":"microsoft","product":"windows_server_2022_23h2"},{"vendor":"microsoft","product":"windows_server_2025"}],"references":[{"url":"https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-20921","tags":["vendor-advisory","patch","Vendor Advisory"]},{"url":"https://www.vicarius.io/vsociety/posts/cve-2026-20921-detection-script-race-condition-vulnerability-in-windows-smb-server"},{"url":"https://www.vicarius.io/vsociety/posts/cve-2026-20921-remediation-script-race-condition-vulnerability-in-windows-smb-server"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-20921"},{"url":"https://github.com/advisories/GHSA-rj95-xj64-7m2x"}],"sources":{"cve":[{"id":"CVE-2026-20921","title":"Windows SMB Server Elevation of Privilege Vulnerability","description":"Concurrent execution using shared resource with improper synchronization ('race condition') in Windows SMB Server allows an authorized attacker to elevate privileges over a 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