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CVE-2026-77888 Microsoft CVE debrief

A type confusion vulnerability in Windows DHCP Server allows an unauthorized attacker to deny service over a network. This CVE was published on 2026-09-08T18:20:38.430Z and was last modified on 2026-09-16T15:07:06.933Z. The NVD entry is currently Analyzed. The vulnerability affects various versions of Windows and Windows Server. Defenders should assess exposure and prioritize patching. The CVSS score is 7.5, indicating a high severity vulnerability. The vulnerability can cause potential service denial in Windows DHCP Server deployments, impacting network availability and reliability.

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

Defenders responsible for Windows DHCP Server deployments should assess exposure and prioritize patching. They should also verify exposure, apply patches from Microsoft, and monitor for potential service denial attempts. The vulnerability can cause potential service denial in Windows DHCP Server deployments, impacting network availability and reliability. Defenders should review the supplied official advisory or CVE

Why it matters

Defenders should care about CVE-2026-77888 because it allows an unauthorized attacker to deny service over a network in Windows DHCP Server deployments. The vulnerability has a CVSS score of 7.5 and affects various versions of Windows and Windows Server. Defenders responsible for these deployments should assess exposure, prioritize patching, and monitor for potential service denial attempts.

  • Potential service denial in Windows DHCP Server deployments
  • Need to verify exposure and apply patches from Microsoft
  • Possible impact on network availability and reliability

Technical summary

The vulnerability is a type confusion issue in Windows DHCP Server, which allows an unauthorized attacker to deny service over a network. The CVSS score is 7.5, and the affected systems include various versions of Windows 10, Windows Server 2012, Windows Server 2016, Windows Server 2019, Windows Server 2022, and Windows Server 2025.

Defensive priority

Defenders should prioritize verifying exposure in Windows DHCP Server deployments and applying patches from Microsoft.

Recommended defensive actions

  • Verify exposure in Windows DHCP Server deployments
  • Apply patches from Microsoft
  • Monitor for potential service denial attempts

Evidence notes

The CVE record and NVD detail page provide information on the vulnerability, including its description, CVSS score, and affected systems. The NVD entry is currently Analyzed. The CVE record was published on 2026-09-08T18:20:38.430Z and has not been modified since then. The vulnerability has a CVSS score of 7.5 and affects various versions of Windows 10, Windows Server 2012, Windows Server 2016, Windows Server 2019, Windows Server 2022, and Windows Server 2025. The evidence is limited,

Sources and references

Verified primary and authoritative sources

  • CVE-2026-77888 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-77888

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

  • CVE-2026-77888 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-77888

    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.