Microsoft Windows SMB Client Improper Access Control Vulnerability

Added to KEV
2025-10-20
Federal due date
2025-11-10
Vendor
Microsoft
Product
Windows
EPSS
97.6th percentile (score 0.443, as of 2026-06-08)
NVD CVSS v3.1
Ransomware use
Unknown
Upstream
https://nvd.nist.gov/vuln/detail/CVE-2025-33073

CISA short description

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.

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.

EPSS percentile is the FIRST.org exploit-probability ranking as of the date noted above; it moves daily. CVSS reflects NVD's analysis at time of publication.