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CVE-2025-33073: Microsoft Windows SMB Client Improper Access Control Vulnerability

• Severity: high (CVSS 8.8 v3.1)
• Exploited in the wild: yes — in CISA KEV since 2025-10-20
• EPSS: 82.7% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2025-06-10 · updated 2026-06-17
• Weakness: CWE-284

Description

Improper access control in Windows SMB allows an authorized attacker to elevate privileges over a network.

Affected products

• Microsoft Windows 10 Version 1507: before 10.0.10240.21034 — fixed in 10.0.10240.21034
• Microsoft Windows 10 1607: before 10.0.14393.8148 — fixed in 10.0.14393.8148
• Microsoft Windows 10: before 10.0.17763.7434 — fixed in 10.0.17763.7434
• Microsoft Windows 10: before 10.0.19044.5965 — fixed in 10.0.19044.5965
• Microsoft Windows 10: before 10.0.19045.5965 — fixed in 10.0.19045.5965
• Microsoft Windows 11: before 10.0.22621.5472 — fixed in 10.0.22621.5472
• Microsoft Windows 11: before 10.0.22631.5472 — fixed in 10.0.22631.5472
• Microsoft Windows 11: before 10.0.26100.4270 — fixed in 10.0.26100.4270
• Microsoft Windows Server 2008: r2-sp1
• Microsoft Windows Server 2012: r2
• Microsoft Windows Server 2016: before 10.0.14393.8148 — fixed in 10.0.14393.8148
• Microsoft Windows Server 2019: before 10.0.17763.7434 — fixed in 10.0.17763.7434
• Microsoft Windows Server 2022: before 10.0.20348.3745 — fixed in 10.0.20348.3745
• Microsoft Windows Server 2022, 23H2 Edition (Server Core installation): before 10.0.25398.1665 — fixed in 10.0.25398.1665
• Microsoft Windows Server 2025: before 10.0.26100.4270 — fixed in 10.0.26100.4270

How to fix

Upgrade to a fixed version: Microsoft Windows 10 Version 1507 10.0.10240.21034; Microsoft Windows 10 1607 10.0.14393.8148; Microsoft Windows 10 10.0.17763.7434; Microsoft Windows 10 10.0.19044.5965; Microsoft Windows 10 10.0.19045.5965; Microsoft Windows 11 10.0.22621.5472; Microsoft Windows 11 10.0.22631.5472; Microsoft Windows 11 10.0.26100.4270; Microsoft Windows Server 2016 10.0.14393.8148; Microsoft Windows Server 2019 10.0.17763.7434; Microsoft Windows Server 2022 10.0.20348.3745; Microsoft Windows Server 2022, 23H2 Edition (Server Core installation) 10.0.25398.1665. Check the vendor advisory for mitigations.

References

• https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-33073
• https://www.vicarius.io/vsociety/posts/cve-2025-33073-detection-script-improper-access-control-in-windows-smb-affects-microsoft-products
• https://www.vicarius.io/vsociety/posts/cve-2025-33073-mitigation-script-improper-access-control-in-windows-smb-affects-microsoft-products
• https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-33073

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