CVE-2026-64397: ksmbd: serialize QUERY_DIRECTORY requests per file

CSIRTS triage

What

The vulnerability involves improper serialization of QUERY_DIRECTORY requests per file in ksmbd.

Who is affected

Users of ksmbd are affected by this issue.

Urgency

Remediation is important to ensure proper handling of directory queries.

Action

Implement the fix for QUERY_DIRECTORY request serialization.

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

Details

Source

Microsoft Security Response Center (INTL · vendor-psirt · site)

Severity

medium — CVSS 5.5

Published

2026-07-14

Exploitation

Not in CISA KEV at last sync

Original advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-64397

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.

• Low exploitation riskCVE-2026-643970.48% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 39% of all scored CVEs.

Referenced CVEs

Same CVEs, other sources

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

• criticalCVE-2026-64397: In the Linux kernel, the following vulnerability has been resolved: ksmbd: serialize QUERY_DIR…nvd

More from Microsoft Security Response Center

• highCVE-2026-42900: Microsoft Windows App Store Elevation of Privilege Vulnerability2026-07-14
• mediumCVE-2026-55003: Windows Remote Desktop Protocol (RDP) Information Disclosure Vulnerability2026-07-14
• highCVE-2026-57992: Microsoft Edge (Chromium-based) Remote Code Execution Vulnerability2026-07-14
• unknownCVE-2026-13867: Chromium: CVE-2026-13867 Inappropriate implementation in Geolocation2026-07-14
• mediumCVE-2026-59926: Mistune: XSS via unescaped class option in Admonition directive2026-07-14