High MSRC-CVE-2026-42903 1 CVE

Windows Kerberos Denial of Service Vulnerability

Published Jun 9, 2026 · Updated Jun 19, 2026 · Revision 3

Vendor: Microsoft

Summary

Impact: Denial of Service. Microsoft rating: Important. Not known to be exploited — Exploitation Unlikely. Customer action: Required.

Details

Security updates
10.0.17763.8880 — https://support.microsoft.com/help/5094123
10.0.20348.5256 — https://support.microsoft.com/help/5094128
10.0.19044.7417 — https://support.microsoft.com/help/5094127
10.0.26100.32995 — https://support.microsoft.com/help/5094125
10.0.26200.8655 — https://support.microsoft.com/help/5094126
10.0.22631.7219 — https://support.microsoft.com/help/5093998
10.0.28000.2269 — https://support.microsoft.com/help/5095051
10.0.14393.9234 — https://support.microsoft.com/help/5094122
6.2.9200.26132 — https://support.microsoft.com/help/5094042
6.3.9600.23228 — https://support.microsoft.com/help/5094041

Vulnerabilities 1

Medium 6.5

CVE-2026-42903

Windows Kerberos Denial of Service Vulnerability

Null pointer dereference in Windows Kerberos allows an authorized attacker to deny service over a network.

Microsoft Windows Server 2019 Windows Server 2019 (Server Core installation) Windows 10 Version 1809 Windows

Jun 9, 2026

Revision history

2026-06-19 #3
Updated an acknowledgement. This is an informational change only.
2026-06-10 #2
Updated an acknowledgement. This is an informational change only.
2026-06-09 #1
Information published.

References

CVE-2026-42903 Windows Kerberos Denial of Service Vulnerability - HTML
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-42903
Microsoft Exploitability Index
https://www.microsoft.com/en-us/msrc/exploitability-index?rtc=1
Microsoft Support Lifecycle
https://support.microsoft.com/lifecycle
Common Vulnerability Scoring System
https://www.first.org/cvss