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CVE-2026-56649: Windows Network File System Remote Code Execution Vulnerability

mediumCVSS 5.9CVE-2026-56649
Concurrent execution using shared resource with improper synchronization ('race condition') in Windows Network File System allows an unauthorized attacker to execute code over a network.

CSIRTS triage

vendor: Microsoftproduct: Windows Network File SystemRemote code execution
What
A race condition in Windows Network File System allows an unauthorized attacker to execute code over a network.
Who is affected
Deployments of Windows Network File System.
Urgency
Remediation is medium urgency due to the potential for remote code execution, though exploitation is not currently observed.
Action
Apply patches when available.

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
medium — CVSS 5.9
Published
2026-07-14
Exploitation
Not in CISA KEV at last sync

Original advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-56649

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-2026-56649coverage & exploitation statusNVD · CVE.org

Same CVEs, other sources

How other CERTs, PSIRTs and databases cover the vulnerabilities in this advisory.

Recent advisories for Windows Network File

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