CVE-2025-33073: Microsoft Windows SMB Client improper access control privilege escalation

CVE-2025-33073 · Severity: critical · CVSS 8.8 · Exploited in the wild · Published 2025-10-20

A vulnerability in the Windows SMB client, which handles file and printer sharing, could allow an attacker to gain elevated permissions on a target system. By tricking a computer into connecting to a malicious server, an attacker can capture authentication details and escalate their access. This flaw is reportedly being exploited in the wild, posing a significant risk to corporate network security and data integrity.

Technologies: Microsoft Windows. Vendors: Microsoft.

Quick answers

Is CVE-2025-33073 exploited in the wild?
Yes. CVE-2025-33073 is known to be exploited in the wild, first recorded on 20 October 2025. Treat it as urgent.
How severe is CVE-2025-33073?
Critical severity, with a CVSS score of 8.8, published 20 October 2025.
Which products and versions are affected?
Microsoft Windows Windows 10, Windows 11, Windows Server 2008, 2012, 2016, 2019, 2022, 2025.
Is there a fix for CVE-2025-33073?
No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
How is CVE-2025-33073 attacked?
It is attacked over the network, in an operating system.
Am I affected by CVE-2025-33073?
Check whether you run Microsoft Windows. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

An improper access control vulnerability (CWE-284) exists in the Microsoft Windows SMB Client. An authenticated attacker with low privileges can execute a malicious script to coerce a victim machine into connecting back to an attacker-controlled system via the SMB protocol. During this connection, the victim machine attempts to authenticate, allowing the attacker to capture or relay authentication credentials to escalate privileges. This vulnerability is reachable over the network and has been added to CISA's Known Exploited Vulnerabilities (KEV) catalog, indicating active exploitation. Patches are available from Microsoft for various versions of Windows and Windows Server.

Affected products

  • Microsoft Windows Windows 10, Windows 11, Windows Server 2008, 2012, 2016, 2019, 2022, 2025

Timeline

  • 2025-06-10: other: CVE received by Microsoft
  • 2025-07-10: other: Initial analysis by NIST
  • 2025-10-20: advisory: Vulnerability published by Microsoft
  • 2025-10-20: kev added: Added to CISA KEV catalog due to active exploitation

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