CVE-2026-64396: ksmbd: fix UAF of struct file_lock in SMB2_LOCK deferred-lock cancellation

mediumCVSS 5.5CVE-2026-64396

CSIRTS triage

Other

What: A use-after-free vulnerability exists in the SMB2_LOCK deferred-lock cancellation process.
Who is affected: Deployments using ksmbd are at risk.
Urgency: Remediation urgency is unknown due to lack of severity information.
Action: Monitor for updates regarding this vulnerability.

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-2026-64396

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-2026-643960.43% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 36% of all scored CVEs.

Referenced CVEs

CVE	CSIRTS overview	External
CVE-2026-64396	coverage & exploitation status	NVD · CVE.org

Same CVEs, other sources

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

highCVE-2026-64396: In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix UAF of struct f…nvd

Recent advisories for ksmbd

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.

highCVE-2026-64437: In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix use-after-free …nvd · 2026-07-25
highCVE-2026-64400: In the Linux kernel, the following vulnerability has been resolved: ksmbd: prevent path traver…nvd · 2026-07-25
criticalCVE-2026-64399: In the Linux kernel, the following vulnerability has been resolved: ksmbd: add permission chec…nvd · 2026-07-25
highCVE-2026-64398: In the Linux kernel, the following vulnerability has been resolved: ksmbd: add a permission ch…nvd · 2026-07-25
criticalCVE-2026-64397: In the Linux kernel, the following vulnerability has been resolved: ksmbd: serialize QUERY_DIR…nvd · 2026-07-25
highCVE-2026-64396: In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix UAF of struct f…nvd · 2026-07-25