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CVE-2026-54109 Microsoft CVE debrief

The CVE-2026-54109 vulnerability is an integer overflow or wraparound issue in the Windows Resilient File System (ReFS). An authorized attacker could exploit this vulnerability to execute code locally. Multiple Windows versions and server releases are affected, including Windows 10, Windows 11, and Windows Server 2016, 2019, 2022, 2025. Microsoft has released patches for this vulnerability.

Vendor
Microsoft
Product
Windows 10 Version 1607
CVSS
HIGH 7.8
CISA KEV
Not listed in stored evidence
Original CVE published
2026-07-14
Original CVE updated
2026-10-08
Advisory published
2026-07-14
Advisory updated
2026-10-08

Who should care

Defenders for Windows environments should assess exposure and apply patches. System administrators and security teams need to prioritize patching affected Windows versions and servers.

Why it matters

CVE-2026-54109 is an integer overflow or wraparound vulnerability in Windows Resilient File System (ReFS) that allows local code execution. Defenders should prioritize patching affected systems, inventory their environment for exposure, and verify ReFS usage.

  • Local code execution possible for authorized attackers
  • Patching required for multiple Windows versions and servers
  • Inventory and verification of ReFS usage necessary

Technical summary

The Windows Resilient File System (ReFS) contains an integer overflow or wraparound vulnerability. An authorized attacker could exploit this issue to execute code locally. Multiple Windows versions are affected, including Windows 10, Windows 11, and Windows Server releases.

Defensive priority

Apply patches immediately for Windows Resilient File System (ReFS) vulnerability

Recommended defensive actions

  • Apply patches for Windows Resilient File System (ReFS) vulnerability
  • Inventory Windows versions and servers to identify exposure
  • Verify ReFS usage in your environment

Evidence notes

The CVE Program and NVD provide official records of the vulnerability. Microsoft has released a patch for this issue. Affected versions and configurations are detailed in the CVE and NVD records.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-54109 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-54109

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

  • CVE-2026-54109 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-54109

    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.