Patch tracker / KB5066840

KB5066840

Microsoft security update released 2025-10-14. Fixes 3 CVEs.

High

Download KB5066840

Get the official update for KB5066840. The download and file size for each supported product are on the Microsoft Update Catalog page.

Microsoft Update Catalog: download KB5066840Microsoft support article

Update summary

Released
2025-10-14
CVEs fixed
3
Max CVSS
8.8
Severity
High

Exploitation and severity

Fixes 3 CVEs. Most severe CVSS 8.8 (High). EPSS exploit probability up to 1.8%.

Among the lower half of tracked Microsoft updates by EPSS exploit probability.

What to do

Moderate priority: schedule it in your normal patch cycle. Senserva flags whether KB5066840 is missing on your devices.

CVEs fixed by this update

CVE-2025-58739CVE-2025-59208CVE-2025-59295

Affected products

  • Windows 10 Version 1809 for 32-bit Systems
  • Windows 11 Version 25H2 for ARM64-based Systems
  • Windows 11 Version 25H2 for x64-based Systems

References

Microsoft support articleMicrosoft Security Update Guide

See this and every Microsoft update ranked by real-world risk on the Microsoft Patch Tracker.

Sponsored by SenservaMicrosoft 365, Intune, Defender, and Entra ID security and compliance, with automated remediation and Trustworthy AI.Scan free
Lexicon: the terms on this page
CVE
Common Vulnerabilities and Exposures. A unique ID for one publicly known vulnerability, such as CVE-2025-1234.
KB
Microsoft Knowledge Base article. The identifier for a specific Microsoft update.
KEV
CISA Known Exploited Vulnerabilities. CVEs confirmed exploited in the wild. Fix these first.
CVSS
Common Vulnerability Scoring System. A standardized Severity score from 0 to 10.
EPSS
Exploit Prediction Scoring System. The probability a CVE will be exploited in the next 30 days.
MSRC
Microsoft Security Response Center. Microsoft's Patch Tuesday advisories and KB-to-CVE mapping.
NVD
National Vulnerability Database (NIST). Authoritative CVE metadata and CVSS scores.
Ransomware
The vulnerability is linked to known ransomware activity.