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CVE-2026-40409: Windows Universal Disk Format File System Driver (UDFS) Elevation of Privilege Vulnerability

highCVSS 7.8CVE-2026-40409

CSIRTS triage

vendor: Microsoftproduct: Windows Universal Disk Format File System Driver (UDFS)Privilege escalation
What
An elevation of privilege vulnerability exists in the UDFS driver.
Who is affected
Users of Windows with the UDFS driver.
Urgency
Remediation is high urgency due to the high severity of the vulnerability.
Action
Install the latest security update for the UDFS driver.

AI-assisted analysis generated from the source advisory — verify against the original.

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Details

Source
Microsoft Security Response Center (INTL · vendor-psirt · site)
Severity
high — CVSS 7.8
Published
2026-06-09
Exploitation
Not in CISA KEV at last sync

Original advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-40409

Exploitation outlook

EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.

Referenced CVEs

CVECSIRTS overviewExternal
CVE-2026-40409coverage & exploitation statusNVD · CVE.org

Recent advisories for Windows Universal Disk

A cluster of recent advisories against the same product widens the attack surface — attackers routinely chain freshly published CVEs on one product, so review these together.

More from Microsoft Security Response Center