CVE-2026-20921
HIGH severity · CVSS 7.5 · CWE-362
7.5CVSS HIGH
Summary
Concurrent execution using shared resource with improper synchronization ('race condition') in Windows SMB Server allows an authorized attacker to elevate privileges over a network.
Impact & exploitability
Attack vectorNetwork
Attack complexityHigh
Privileges requiredLow
User interactionNone
Confidentiality impactHigh
Integrity impactHigh
Availability impactHigh
Exploit probability (EPSS)1%
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
Affected products we track (4)
Recommendation
Apply the vendor fix promptly. Open any affected product above for its exact safe version.
Additional information
- NVD record
- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-20921Advisory
- https://www.vicarius.io/vsociety/posts/cve-2026-20921-detection-script-race-condition-vulnerability-in-windows-smb-server
- https://www.vicarius.io/vsociety/posts/cve-2026-20921-remediation-script-race-condition-vulnerability-in-windows-smb-server