# CVE-2026-64138: ksmbd: validate SID in parent security descriptor during ACL inheritance

CVE-2026-64138 is fixed in linux on 1 platform, first by DEBIAN-CVE-2026-64138, released July 20, 2026. It is not reported as exploited. Patch Radar priority: Urgent.

- Web page: https://patchblox.com/security/cve/CVE-2026-64138
- Priority: Urgent
- CVSS: 9.8 (Critical)
- EPSS: 0.0045
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Jul 19, 2026
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-64138

## 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.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 13.5 (trixie) | 6.12.94-1 | [DEBIAN-CVE-2026-64138](https://patchblox.com/security/data/fix/linux/debian-cve-2026-64138.md) | Jul 20, 2026 |
| Linux | linux Debian 14 | 7.0.12-1 | [DEBIAN-CVE-2026-64138](https://patchblox.com/security/data/fix/linux/debian-cve-2026-64138.md) | Jul 20, 2026 |

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Data as of 2026-11-08T13:06:02Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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