CVE-2026-64138 ksmbd: validate SID in parent security descriptor during ACL inheritance
Attackers can bypass ACL inheritance checks in ksmbd by manipulating SIDs, potentially gaining unauthorized access or privileges.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-64138?
CVE-2026-64138 is a high-severity missing authorization vulnerability in Linux kernel, published on 19 Jul 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
ksmbd: validate SID in parent security descriptor during ACL inheritance
Introduce smb_validate_ntsd_sid() helper to safely validate Owner SID and Group SID inside the NT Security Descriptor (smb_ntsd) retrieved from the parent directory.
Which versions are affected by CVE-2026-64138?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-64138?
Apply the vendor's patch.
Upgrade, and check permissions on every request on the server, not only in the interface. More about Missing authorization.
Is CVE-2026-64138 being exploited?
There is no known exploitation of CVE-2026-64138 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2026-64138, DEBIAN-CVE-2026-64138, GHSA-23jx-58r9-pwv6, ROOT-OS-DEBIAN-12-CVE-2026-64138, ROOT-OS-UBUNTU-2204-CVE-2026-64138, UBUNTU-CVE-2026-64138.