Microsoft Windows SMB Client Improper Access Control Vulnerability

[ Why it matters ]Priority signals

• Exploited in the wild: on CISA's Known Exploited Vulnerabilities list since 2025-10-20
• EPSS: 83% chance of exploitation in the next 30 days (higher than 100% of CVEs)

[ Description ]Official description

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

CISA: 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.

[ Fixes ]Fixes and patches

CISA required action (US federal deadline 10 Nov 2025): Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

No fix or interim patch is linked from our sources yet. Check the vendor references below and limit exposure of affected systems until a fix is available.

[ References ]References

• msrc.microsoft.com/update-guide/vulnerability/CVE-2025-33073Vendor Advisory
• www.vicarius.io/vsociety/posts/cve-2025-33073-detection-script-improper-access-control-…Third Party Advisory
• www.vicarius.io/vsociety/posts/cve-2025-33073-mitigation-script-improper-access-control…MitigationThird Party Advisory
• www.cisa.gov/known-exploited-vulnerabilities-catalogUS Government Resource