PT-2026-2726 · Microsoft · Windows Smb Server+1

Published 2026-01-13 · Updated 2026-05-26 · CVE-2026-20921

Positive Technologies (AI Summary)

CVSS v3.1

7.5

High

Base vector

AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H

Name of the Vulnerable Software and Affected Versions Windows SMB Server (affected versions not specified)

Description A flaw in Windows SMB Server related to concurrent execution using a shared resource with improper synchronization, specifically a race condition, could allow an authorized attacker to gain elevated privileges on a network. This issue allows attackers to affect the system and elevate privileges.

Recommendations At the moment, there is no information about a newer version that contains a fix for this vulnerability.

Race Condition

Weakness Enumeration

CWE-362

Related Identifiers

BDU:2026-00445

CVE-2026-20921

Affected Products

Windows

Windows Smb Server

References · 10

• https://msrc.microsoft.com/update-guide/en-US/advisory/CVE-2026-20921 · Vendor Advisory
• https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-20921 · Vendor Advisory
• https://bdu.fstec.ru/vul/2026-00445 · Security Note
• https://nvd.nist.gov/vuln/detail/CVE-2026-20921 · Security Note
• https://osv.dev/vulnerability/CVE-2026-20921 · Vendor Advisory
• http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2026-20921 · Security Note
• https://vicarius.io/vsociety/posts/cve-2026-20921-remediation-script-race-condition-vulnerability-in-windows-smb-server · Note
• https://t.me/cveNotify/164739 · Telegram Post
• https://twitter.com/CVEnew/status/2011759656691974335 · Twitter Post
• https://vicarius.io/vsociety/posts/cve-2026-20921-detection-script-race-condition-vulnerability-in-windows-smb-server · Note