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PatchSiren cyber security CVE debrief

CVE-2026-78446 Microsoft CVE debrief

A use-after-free vulnerability in Windows Distributed File System (DFS) allows an authorized attacker to deny service over a network. This CVE has been assessed as having a CVSS score of 5.3 and a severity of MEDIUM. Microsoft has provided a patch for this vulnerability. System administrators and defenders responsible for Windows DFS systems should assess exposure and apply patches or mitigations to prevent service denial. The vulnerability exists in the Windows Distributed File System (DFS) and allows an authorized attacker to deny service over a network.

Vendor
Microsoft
Product
Windows 10 Version 1607
CVSS
MEDIUM 5.3
CISA KEV
Not listed in stored evidence
Original CVE published
2026-09-08
Original CVE updated
2026-09-11
Advisory published
2026-09-08
Advisory updated
2026-09-11

Who should care

System administrators and defenders responsible for Windows DFS systems should assess exposure and apply patches or mitigations to prevent service denial.

Why it matters

This vulnerability allows an authorized attacker to deny service over a network. Defenders should assess exposure and apply patches or mitigations to prevent service denial.

  • Verify and apply patches or updates to vulnerable Windows DFS systems to prevent service denial
  • Monitor systems for potential service denial
  • Assess exposure of Windows DFS systems to this vulnerability

Technical summary

The vulnerability exists in the Windows Distributed File System (DFS) and allows an authorized attacker to deny service over a network. The vulnerability has been assessed as having a CVSS score of 5.3 and a severity of MEDIUM. This vulnerability can be mitigated by applying patches or updates to vulnerable Windows DFS systems, verifying and applying updates for Windows 10, Windows 11, and Windows Server systems, and monitoring systems for potential service denial.

Defensive priority

Apply patches or mitigations to vulnerable Windows DFS systems to prevent service denial.

Recommended defensive actions

  • Apply patches or mitigations to vulnerable Windows DFS systems
  • Verify and apply updates for Windows 10, Windows 11, and Windows Server systems
  • Monitor systems for potential service denial

Evidence notes

The CVE record and NVD detail page provide information on the vulnerability, including its description, CVSS score, and affected systems. The CVE record was published on 2026-09-08T18:20:42.417Z and has not been modified since then. The NVD entry is currently Analyzed. There are no additional details on the affected systems or exploitation attempts.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-78446 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-78446

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

  • CVE-2026-78446 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-78446

    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.