CVE-2026-20934
published 2026-01-13CVE-2026-20934: Concurrent execution using shared resource with improper synchronization ('race condition') in Windows SMB Server allows an authorized attacker to elevate…
PriorityP353high7.5CVSS 3.1
AVNACHPRLUINSUCHIHAH
EPSS
0.78%
51.9th percentile
Concurrent execution using shared resource with improper synchronization ('race condition') in Windows SMB Server allows an authorized attacker to elevate privileges over a network.
Affected
41 ranges· showing 25
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| microsoft | windows_10_1607 | < 10.0.14393.8783 | 10.0.14393.8783 |
| microsoft | windows_10_1809 | < 10.0.17763.8276 | 10.0.17763.8276 |
| microsoft | windows_10_21h2 | < 10.0.19044.6809 | 10.0.19044.6809 |
| microsoft | windows_10_22h2 | < 10.0.19045.6809 | 10.0.19045.6809 |
| microsoft | windows_10_version_1607 | >= 10.0.14393.0 < 10.0.14393.8783 | 10.0.14393.8783 |
| microsoft | windows_10_version_1809 | >= 10.0.17763.0 < 10.0.17763.8276 | 10.0.17763.8276 |
| microsoft | windows_10_version_21h2 | >= 10.0.19044.0 < 10.0.19044.6809 | 10.0.19044.6809 |
| microsoft | windows_10_version_22h2 | >= 10.0.19045.0 < 10.0.19045.6809 | 10.0.19045.6809 |
| microsoft | windows_11_23h2 | < 10.0.22631.6491 | 10.0.22631.6491 |
| microsoft | windows_11_24h2 | < 10.0.26100.7623 | 10.0.26100.7623 |
| microsoft | windows_11_25h2 | < 10.0.26200.7623 | 10.0.26200.7623 |
| microsoft | windows_11_version_22h3 | >= 10.0.22631.0 < 10.0.22631.6491 | 10.0.22631.6491 |
| microsoft | windows_11_version_23h2 | >= 10.0.22631.0 < 10.0.22631.6491 | 10.0.22631.6491 |
| microsoft | windows_11_version_24h2 | >= 10.0.26100.0 < 10.0.26100.7623 | 10.0.26100.7623 |
| microsoft | windows_11_version_25h2 | >= 10.0.26200.0 < 10.0.26200.7623 | 10.0.26200.7623 |
| microsoft | windows_server_2012 | — | — |
| microsoft | windows_server_2012 | >= 6.2.9200.0 < 6.2.9200.25868 | 6.2.9200.25868 |
| microsoft | windows_server_2012_r2 | >= 6.3.9600.0 < 6.3.9600.22968 | 6.3.9600.22968 |
| microsoft | windows_server_2016 | < 10.0.14393.8783 | 10.0.14393.8783 |
| microsoft | windows_server_2016 | >= 10.0.14393.0 < 10.0.14393.8783 | 10.0.14393.8783 |
| microsoft | windows_server_2019 | < 10.0.17763.8276 | 10.0.17763.8276 |
| microsoft | windows_server_2019 | >= 10.0.17763.0 < 10.0.17763.8276 | 10.0.17763.8276 |
| microsoft | windows_server_2022 | < 10.0.20348.4648 | 10.0.20348.4648 |
| microsoft | windows_server_2022 | >= 10.0.20348.0 < 10.0.20348.4648 | 10.0.20348.4648 |
| microsoft | windows_server_2022_23h2 | < 10.0.25398.2092 | 10.0.25398.2092 |
CVSS provenance
nvdv3.17.5HIGHCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
vendor_msrc7.5HIGH
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GHSA
GHSA-7mp9-fp3j-g5hq: Concurrent execution using shared resource with improper synchronization ('race condition') in Windows SMB Server allows an authorized attacker to ele
ghsa_unreviewed·2026-01-13
CVE-2026-20934 [HIGH] CWE-362 GHSA-7mp9-fp3j-g5hq: Concurrent execution using shared resource with improper synchronization ('race condition') in Windows SMB Server allows an authorized attacker to ele
Concurrent execution using shared resource with improper synchronization ('race condition') in Windows SMB Server allows an authorized attacker to elevate privileges over a network.
Microsoft
Windows SMB Server Elevation of Privilege Vulnerability
vendor_msrc·2026-01-13·CVSS 7.5
CVE-2026-20934 [HIGH] CWE-362 Windows SMB Server Elevation of Privilege Vulnerability
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.
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.
FAQ: What privileges could be gained by an attacker who successfully exploited this vulnerability?
An attacker who successfully exploited this vulnerability could gain SYSTEM privileges.
Windows SMB Server: Windows SMB Server
Microsoft: Microsoft
Customer Action Required: Yes
Impact: Elevation of Privilege
Exploit Status: Publicly
No detection rules found.
No public exploits indexed.
Bleepingcomputer
Microsoft January 2026 Patch Tuesday fixes 3 zero-days, 114 flaws
blogs_bleepingcomputer·2026-01-13·CVSS 5.5
[MEDIUM] Microsoft January 2026 Patch Tuesday fixes 3 zero-days, 114 flaws
## Microsoft January 2026 Patch Tuesday fixes 3 zero-days, 114 flaws
## Lawrence Abrams
57 Elevation of Privilege vulnerabilities
3 Security Feature Bypass vulnerabilities
22 Remote Code Execution vulnerabilities
22 Information Disclosure vulnerabilities
2 Denial of Service vulnerabilities
5 Spoofing vulnerabilities
When BleepingComputer reports on Patch Tuesday security updates, we only count those released by Microsoft today. Therefore, the number of flaws does not include Microsoft Edge (1 flaw) and Mariner vulnerabilities fixed earlier this month.
To learn more about the non-security updates released today, you can review our dedicated articles on the Windows 11 KB5074109 & KB5073455 cumulative updates and Windows 10 KB5073724 extended security update .
## 3 zero-days, one ex
Wiz
CVE-2026-20934 Impact, Exploitability, and Mitigation Steps | Wiz
blogs_wiz·CVSS 7.5
CVE-2026-20934 [HIGH] CVE-2026-20934 Impact, Exploitability, and Mitigation Steps | Wiz
## CVE-2026-20934 :
vulnerability analysis and mitigation
Concurrent execution using shared resource with improper synchronization ('race condition') in Windows SMB Server allows an authorized attacker to elevate privileges over a network.
Source : NVD
## 7.5
Score
Published January 13, 2026
Severity HIGH
CNA Score 7.5
Has Public Exploit No
Has CISA KEV Exploit No
CISA KEV Release Date N/A
CISA KEV Due Date N/A
Exploitation Probability Percentile (EPSS) 16.3
Exploitation Probability (EPSS) 0.1
Sources
NVD
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2026-01-13
Published