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MSRC compact vulnerability detail

CVE-2026-20927 · Windows SMB Server Denial of Service Vulnerability

Concurrent execution using shared resource with improper synchronization ('race condition') in Windows SMB Server allows an authorized attacker to deny service over a network.

Severity
Important
Impact
Denial of Service
CVSS
5.3 base · 4.6 temporal
Release
2026-01-13
Signals
Windows SMB Server Denial of Service Exploited: No Publicly disclosed: No Exploitability: Exploitation Unlikely
CWE
CWE-362: Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')
Patch Diff
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Description
Concurrent execution using shared resource with improper synchronization ('race condition') in Windows SMB Server allows an authorized attacker to deny service over a network.
FAQ / Articles
Windows SMB Server Denial of Service Vulnerability
Concurrent execution using shared resource with improper synchronization ('race condition') in Windows SMB Server allows an authorized attacker to deny service over a network.
FAQ
According to the CVSS metric, the attack complexity is high (AC:H). What does that mean for this vulnerability? Successful exploitation of this vulnerability requires an attacker to win a race condition.