CVE-2026-64437: ksmbd: fix use-after-free of a deferred file_lock on SMB2_CLOSE then SMB2_CANCEL
CSIRTS triage
- What
- A use-after-free vulnerability occurs with a deferred file lock during SMB2_CLOSE and SMB2_CANCEL operations.
- Who is affected
- Deployments using the ksmbd SMB server.
- Urgency
- Remediation is necessary to prevent potential crashes, though no known exploits exist.
- Action
- Update the ksmbd server to the latest version.
AI-assisted analysis generated from the source advisory — verify against the original.
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Details
Original advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-64437
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-2026-644370.43% 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-2026-64437 | coverage & exploitation status | NVD · CVE.org |
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