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PatchSiren cyber security CVE debrief

CVE-2026-42903 Microsoft CVE debrief

CVE-2026-42903 is a vulnerability in Windows Kerberos that allows an authorized attacker to deny service over a network. The vulnerability has a CVSS score of 6.5 and a severity of MEDIUM. It was published on 2026-06-09T17:17:09.800Z and modified on 2026-06-11T16:17:05.920Z.

Vendor
Microsoft
Product
Windows 10 Version 1607
CVSS
MEDIUM 6.5
CISA KEV
Not listed in stored evidence
Original CVE published
2026-06-09
Original CVE updated
2026-06-11
Advisory published
2026-06-09
Advisory updated
2026-06-11

Who should care

Administrators of Windows systems, particularly those using Kerberos for authentication, should be aware of this vulnerability and take necessary steps to mitigate it.

Technical summary

The vulnerability is caused by a null pointer dereference in Windows Kerberos. An authorized attacker can exploit this vulnerability to deny service over a network.

Defensive priority

MEDIUM

Recommended defensive actions

  • Apply patches from Microsoft as they become available. See [ref-4](https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-42903) for more information.

Evidence notes

The CVE record [cve-org] and NVD detail [nvd] provide additional information about this vulnerability.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-42903 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-42903

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-42903 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-42903

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.