ksmbd: validate SID in parent security descriptor during ACL inheritance (CVE-2026-64138) | HOL Guard CVE

High · CVSS 8.8CVE-2026-64138

ksmbd: validate SID in parent security descriptor during ACL inheritance

Answer in brief

CVE-2026-64138 records a High severity (CVSS 8.8) vulnerability in ksmbd: validate SID in parent security descriptor during ACL inheritance. The current sources do not mark it as known exploited. The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Jul 19, 2026Updated Aug 18, 2026Source checked Sep 20, 2026First seen by HOL Aug 5, 2026Material review Aug 18, 2026

Upstream Advisory

Key facts

Risk: High · CVSS 8.8
Exploitation: Not marked as known exploited
Affected software: 7 mapped packages or products
Fix availability: Available

Why this deserves its current priority

CVSS is 8.8. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.

Affected products and reported versions
Product	Affected versions	Fixed versions
cpe:2.3:o:linux:linux_kernel::::::::	Not reported	Not reported
cpe:2.3:o:linux:linux_kernel:7.1:rc1::::::	Not reported	Not reported
cpe:2.3:o:linux:linux_kernel:7.1:rc2::::::	Not reported	Not reported
cpe:2.3:o:linux:linux_kernel:7.1:rc3::::::	Not reported	Not reported
cpe:2.3:o:linux:linux_kernel:7.1:rc4::::::	Not reported	Not reported

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
Linux/Linuxgeneric	>=e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 <f0e5c9c663badc9982e6941322eef1cb17de0f11 \|\| >=e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 <18d8db24b0a5b7be4829238dd4022236df02d421 \|\| >=e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 <1c9d0646a9959752f11ca1080dc1ff26bd1756cb \|\| >=e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 <69f030cf95488ae1186c72ac8c66fd279664ea7f	f0e5c9c663badc9982e6941322eef1cb17de0f11, 18d8db24b0a5b7be4829238dd4022236df02d421, 1c9d0646a9959752f11ca1080dc1ff26bd1756cb, 69f030cf95488ae1186c72ac8c66fd279664ea7f
Linux/Linuxgeneric	5.15	Not reported

Recommended response

Check inventory. Check lockfiles and deployed manifests for Linux/Linux, Linux/Linux.
Review the reported fix. Update Linux/Linux to f0e5c9c663badc9982e6941322eef1cb17de0f11 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Jul 19, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Aug 18, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Aug 5, 2026

Sources and claim methodology

Upstream source 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.

Quoted source text, attributed separately from HOL analysis.