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At a glance
- CVE-2026-64138 is an out-of-bounds read in Linux Kernel ksmbd.
- The flaw could expose sensitive information; only systems with ksmbd enabled are affected.
- A remote attacker must be authenticated; CVSS 7.1.
- Prioritize updating the kernel through the Linux vendor.
Linux Kernel ksmbd out-of-bounds read could expose sensitive information
Zero Day Initiative disclosed CVE-2026-64138 in Linux Kernel ksmbd: an out-of-bounds read could expose sensitive information. Only systems with ksmbd enabled are affected; prioritize updating the kernel through the Linux vendor.
In this article
Zero Day Initiative published an advisory about an out-of-bounds read in ksmbd, the SMB server component in Linux Kernel. Administrators should determine whether ksmbd is enabled and check for kernel updates from their Linux vendor. View the Zero Day Initiative advisory.
Overview and technical details
CVE-2026-64138 occurs when ksmbd processes an inherited security descriptor without correctly validating user-provided data. This leads to a read beyond the end of an allocated buffer and could expose sensitive information.
| Field | Details |
|---|---|
| Product | ksmbd in Linux Kernel |
| CVE | CVE-2026-64138 |
| CVSS | 7.1 (AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:N/A:L) |
| Source | Zero Day Initiative |
The flaw could be combined with another vulnerability to execute arbitrary code in the kernel context. This is a stated possibility involving a combination, not a claim that CVE-2026-64138 alone allows code execution.
Affected systems
Only systems with ksmbd enabled are affected. A remote attacker must be authenticated. Systems without ksmbd enabled are not affected.
System checks
Check the running kernel version and compare it with updates from the Linux vendor.
uname -rCheck whether the ksmbd module is loaded. If ksmbd appears in the output, the system meets the exposure condition stated in the advisory.
lsmod | grep '^ksmbd'
Remediation and mitigation
Prioritize updating the kernel on systems with ksmbd enabled; identify the applicable update from the Linux vendor in use.
The advisory references this fix: commit 69f030cf95488ae1186c72ac8c66fd279664ea7f.
References
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