Out-of-bounds read in Linux kernel - CVE-2026-64138
Published: July 20, 2026
Vulnerability identifier: #VU138502
CSH Severity: Medium
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Green
CVE-ID: CVE-2026-64138
CWE-ID: CWE-125
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: Linux Foundation
Affected software:
Linux kernel
Linux kernel
Detailed vulnerability description
The vulnerability allows a remote user to cause a denial of service.
The vulnerability exists due to an out-of-bounds read in the ksmbd smbacl.c ACL inheritance logic when processing owner and group SIDs from a parent security descriptor. A remote user can provide a specially crafted parent security descriptor to cause a denial of service.
The issue occurs during ACL inheritance in ksmbd.
How to mitigate CVE-2026-64138
Install security update from vendor's repository.