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PatchSiren cyber security CVE debrief

CVE-2026-77890 Microsoft CVE debrief

A type confusion vulnerability in Windows DHCP Server allows an unauthorized attacker to deny service over a network. The vulnerability has a CVSS score of 7.5 and is classified as HIGH severity. Microsoft has released a patch for this vulnerability. Windows DHCP Server administrators should assess exposure and apply patches immediately. The vulnerability can be exploited to deny service over a network, and its CVSS score indicates high severity. Microsoft's patch addresses the type confusion issue.

Vendor
Microsoft
Product
Windows 10 Version 1607
CVSS
HIGH 7.5
CISA KEV
Not listed in stored evidence
Original CVE published
2026-09-08
Original CVE updated
2026-09-16
Advisory published
2026-09-08
Advisory updated
2026-09-16

Who should care

Windows DHCP Server administrators and vulnerability management teams should assess exposure and apply patches immediately. This involves reviewing the affected systems, applying the Microsoft patch, and verifying that the patch has been successfully applied. Additionally, vulnerability management teams should update their processes to ensure timely patching of similar vulnerabilities in the future.

Why it matters

CVE-2026-77890 is a type confusion vulnerability in Windows DHCP Server that allows an unauthorized attacker to deny service over a network. Windows DHCP Server administrators and vulnerability management teams should assess exposure and apply patches immediately. The vulnerability has a CVSS score of 7.5 and is classified as HIGH severity. Microsoft has released a patch for this vulnerability.

  • Potential denial of service over a network.
  • Requires verification of affected versions and patching status.
  • May require updates to vulnerability management processes.

Technical summary

The vulnerability is a type confusion issue in Windows DHCP Server, which can be exploited to deny service over a network. The CVE record and NVD detail page provide official information about this vulnerability. Microsoft has released a patch for this vulnerability.

Defensive priority

Apply patches immediately, especially for Windows DHCP Server installations.

Recommended defensive actions

  • Apply patches immediately, especially for Windows DHCP Server installations.
  • Review and update vulnerability management processes to ensure timely patching.
  • Monitor Windows DHCP Server installations for potential exploitation attempts.

Evidence notes

The vulnerability is described as a type confusion issue in Windows DHCP Server, which can be exploited to deny service over a network. The CVE record and NVD detail page provide official information about this vulnerability.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-77890 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-77890

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

  • CVE-2026-77890 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-77890

    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.