Review reviewHigh

CVE-2026-64138

Linux

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.

CVSS: 8.8
EPSS: -
CISA KEV: Not listed
Published: 2026.07.20

PRIORITY ASSESSMENT

Review review

The CVSS severity warrants an early asset and exposure review.

Known exploitationNot established by KEV

Exploit probability-

Technical severityCVSS 8.8

Vulnerability overview

Affected product and versions

Product: Linux
Affected versions: >= e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 < f0e5c9c663badc9982e6941322eef1cb17de0f11, >= e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 < 18d8db24b0a5b7be4829238dd4022236df02d421, >= e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 < 1c9d0646a9959752f11ca1080dc1ff26bd1756cb, >= e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 < 69f030cf95488ae1186c72ac8c66fd279664ea7f, >= 5.15
Fixed versions: No verified fixed-version field is available yet

Recommended response sequence

Confirm exposure before applying a vendor-supported change.

Full remediation guide

1
Identify
Confirm that Linux and an affected version are present.
2
Prioritize
Combine exploitation signals with asset exposure and business criticality.
3
Remediate
Follow the vendor advisory or supported update path and preserve rollback options.
4
Verify
Recheck the version, service health, access paths, and relevant logs.

Technical data

CVSS vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CWE: Not available