CVE entry · CVE-2025-33073
CVE-2025-33073: Microsoft Windows SMB Client Improper Access Control Vulnerability
Microsoft Windows SMB Client contains an improper access control vulnerability that could allow for privilege escalation. An attacker could execute a specially crafted malicious script to coerce the victim machine to connect back to the attack system using SMB and authenticate.
- Actively exploited: added to CISA’s KEV catalog on October 20, 2025.
- Use by ransomware: not established so far.
- Remediation deadline for US federal agencies: November 10, 2025.
Description from CISA’s KEV catalog.
What to do
- Check whether your estate includes Microsoft Windows, including internet-facing devices.
- Apply the vendor’s patch or mitigations (references below). Failing that, isolate the product or stop using it, as CISA requires of US federal agencies.
- An exploited vulnerability has often been used before it was fixed: look for signs of compromise, especially on internet-facing devices.
References
- Vendor advisory or reference cited by CISA (msrc.microsoft.com)
- NVD entry (NIST)
- CISA KEV catalog
Other Microsoft vulnerabilities
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Microsoft Windows Command Injection Vulnerability
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Microsoft SharePoint Code Injection Vulnerability
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Microsoft Windows Heap-Based Buffer Overflow Vulnerability
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Microsoft Windows Link Following Vulnerability
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Microsoft SQL Server Remote Code Execution Vulnerability
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Microsoft SharePoint Weak Authentication Vulnerability