CyberSecBulletin
CVE-2025-33073Exploited in the wildNVD status: Analyzed

Microsoft Windows SMB Client Improper Access Control

Published Updated By the CyberSecBulletin desk

CVE-2025-33073 is a high-severity improper access control vulnerability in Windows 10 Version 1507 from Microsoft, with a CVSS 3.1 base score of 8.8 out of 10. It can be exploited remotely over the network by an attacker with a low-privileged account, without any action from a user. The record lists version 10.0.10240.21034 as the first without the flaw, so updating Windows 10 Version 1507 to that release or later removes the exposure. CISA added it to the Known Exploited Vulnerabilities catalogue on October 20, 2025, which means attacks have been observed in the wild.

Patch now

Attackers are already exploiting this vulnerability, according to CISA.

What to do

  1. Update Windows 10 Version 1507 to 10.0.10240.21034 or a later version.
  2. Update Windows 10 Version 1607 to 10.0.14393.8148 or a later version.
  3. Update Windows 10 Version 1809 to 10.0.17763.7434 or a later version.
  4. CISA's required action: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
  5. Read the advisory on msrc.microsoft.com for workarounds and exact fixed builds.

Affected products and versions

VendorProductAffected versionsFixed in
MicrosoftWindows 10 Version 150710.0.10240.0 up to, but not including, 10.0.10240.2103410.0.10240.21034
MicrosoftWindows 10 Version 160710.0.14393.0 up to, but not including, 10.0.14393.814810.0.14393.8148
MicrosoftWindows 10 Version 180910.0.17763.0 up to, but not including, 10.0.17763.743410.0.17763.7434
MicrosoftWindows 10 Version 21H210.0.19044.0 up to, but not including, 10.0.19044.596510.0.19044.5965
MicrosoftWindows 10 Version 22H210.0.19045.0 up to, but not including, 10.0.19045.596510.0.19045.5965
MicrosoftWindows 11 version 22H210.0.22621.0 up to, but not including, 10.0.22621.547210.0.22621.5472
MicrosoftWindows 11 version 22H310.0.22631.0 up to, but not including, 10.0.22631.547210.0.22631.5472
MicrosoftWindows 11 Version 23H210.0.22631.0 up to, but not including, 10.0.22631.547210.0.22631.5472
MicrosoftWindows 11 Version 24H210.0.26100.0 up to, but not including, 10.0.26100.434910.0.26100.4349
MicrosoftWindows Server 2008 R2 Service Pack 16.1.7601.0 up to, but not including, 6.1.7601.277696.1.7601.27769
MicrosoftWindows Server 2008 R2 Service Pack 1 (Server Core installation)6.1.7601.0 up to, but not including, 6.1.7601.277696.1.7601.27769
MicrosoftWindows Server 2008 Service Pack 26.0.6003.0 up to, but not including, 6.0.6003.233516.0.6003.23351
MicrosoftWindows Server 2008 Service Pack 2 (Server Core installation)6.0.6003.0 up to, but not including, 6.0.6003.233516.0.6003.23351
MicrosoftWindows Server 20126.2.9200.0 up to, but not including, 6.2.9200.255226.2.9200.25522
MicrosoftWindows Server 2012 (Server Core installation)6.2.9200.0 up to, but not including, 6.2.9200.255226.2.9200.25522
MicrosoftWindows Server 2012 R26.3.9600.0 up to, but not including, 6.3.9600.226206.3.9600.22620
MicrosoftWindows Server 2012 R2 (Server Core installation)6.3.9600.0 up to, but not including, 6.3.9600.226206.3.9600.22620
MicrosoftWindows Server 201610.0.14393.0 up to, but not including, 10.0.14393.814810.0.14393.8148
MicrosoftWindows Server 2016 (Server Core installation)10.0.14393.0 up to, but not including, 10.0.14393.814810.0.14393.8148
MicrosoftWindows Server 201910.0.17763.0 up to, but not including, 10.0.17763.743410.0.17763.7434
MicrosoftWindows Server 2019 (Server Core installation)10.0.17763.0 up to, but not including, 10.0.17763.743410.0.17763.7434
MicrosoftWindows Server 202210.0.20348.0 up to, but not including, 10.0.20348.380710.0.20348.3807
MicrosoftWindows Server 2022, 23H2 Edition (Server Core installation)10.0.25398.0 up to, but not including, 10.0.25398.166510.0.25398.1665
MicrosoftWindows Server 202510.0.26100.0 up to, but not including, 10.0.26100.434910.0.26100.4349
MicrosoftWindows Server 2025 (Server Core installation)10.0.26100.0 up to, but not including, 10.0.26100.434910.0.26100.4349

Version data comes from the organisation that assigned the CVE; 10 further products are omitted here. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
NetworkCan be exploited remotely over a network, including the internet.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
LowA basic user account is enough.
User interaction
NoneNo action by a victim is required.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
HighAll data handled by the component can be read.
Integrity
HighData or code can be modified at will.
Availability
HighThe component can be taken down completely.

Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H. Scored by CNA (microsoft.com).

Official description

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

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Improper Access Control

The product does not restrict or incorrectly restricts access to a resource from an unauthorized actor.

How developers prevent this class of flaw

  • Very carefully manage the setting, management, and handling of privileges. Explicitly manage trust zones in the software.
  • Compartmentalize the system to have safe areas where trust boundaries can be unambiguously drawn. Do not allow sensitive data to go outside of the trust boundary and always be careful when interfacing with a compartment outside of the safe area. Ensure that appropriate compartmentalization is built into the system design, and the compartmentalization allows for and reinforces privilege separation functionality. Architects and designers should rely on the principle of least privilege to decide the appropriate time to use privileges and the time to drop privileges.

More Improper Access Control vulnerabilities (CWE-284)

Timeline

  1. CVE record published.
  2. Added to CISA's Known Exploited Vulnerabilities catalogue.
  3. CISA published its SSVC assessment (exploitation: active, automatable: no, technical impact: total).
  4. Deadline for US federal agencies to remediate, set by CISA.
  5. Record last changed materially (score, affected products, status or references).

References

Other vulnerabilities in Windows 10 Version 1507

All Windows 10 Version 1507 vulnerabilities

Recent Improper Access Control vulnerabilities

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