What is CVE-2026-64391?

CVE-2026-64391 is a Critical severity Linux kernel vulnerability with a CVSS score of 9.8 out of 10, affecting Linux kernel versions from 5.15 onward and patched in 6.12.96, 6.18.39, 7.1.4 and others. CVE-2026-64391 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

What is the CVSS score for CVE-2026-64391?

CVE-2026-64391 has a CVSS score of 9.8 out of 10, rated Critical severity. The vector string is CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

Is there a patch available for CVE-2026-64391?

Yes, CVE-2026-64391 has been patched. Fixed versions include 6.12.96, 6.18.39, 7.1.4 and others. If you are running Linux kernel 5.15 or later up to the fix versions, apply the relevant patch for your kernel branch.

Is CVE-2026-64391 actively exploited?

CVE-2026-64391 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

CVE-2026-64391

Critical

In the Linux kernel, the following vulnerability has been resolved: ksmbd: use opener credentials for ADS I/O Alternate data streams are stored as xattrs. Unlike regular file I/O, their read and write paths therefore call VFS xattr helpers which recheck inode permissions and LSM policy using the current task credentials. Run ADS I/O with the credentials captured when the SMB handle was opened.

Package Linux Kernel

Published 2026-07-25

Last modified 2026-09-04

CVSS version 3.1

Patch available

Yes

CVSS 3.1 score

9.8

out of 10

Critical

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Vector string

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected versions

Linux kernel versions 5.15 and later are affected. Fixed in 6.12.96, 6.18.39, 7.1.4, 7.2 and their respective stable series.

Affected from

≥ 5.15

Fixed in

✓ 6.12.96 6.12.x ✓ 6.18.39 6.18.x ✓ 7.1.4 7.1.x ✓ 7.2

References

4 total

Kernel Git
https://git.kernel.org/stable/c/2b4592cea214683de0f2ce6f8c22c097fb0ea1ab

Patch
Kernel Git
https://git.kernel.org/stable/c/52a56cf53ec834c44ac1b4d16d585f26613ee5ce

Patch
Kernel Git
https://git.kernel.org/stable/c/a8f5d39971bbad9340d49cd41b0e2da9452a649d

Patch
Kernel Git
https://git.kernel.org/stable/c/baa5e094886fffa7e6272edcb5e08be5ce28262c

Patch

Details

CVE ID CVE-2026-64391

Severity Critical

CVSS score 9.8 / 10

CVSS version 3.1

Published 2026-07-25

Modified 2026-09-04

KEV No

Patch

Yes

Package linux

Frequently asked questions

What is CVE-2026-64391?

CVE-2026-64391 is a Critical severity Linux kernel vulnerability with a CVSS score of 9.8 out of 10 . It affects Linux kernel versions from 5.15 onward and has been patched in 6.12.96, 6.18.39, 7.1.4 and others. CVE-2026-64391 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.
What is the CVSS score for CVE-2026-64391?

CVE-2026-64391 has a CVSS score of 9.8 out of 10, rated Critical severity (CVSS 3.1). The vector string is CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.
Is there a patch available for CVE-2026-64391?

Yes. CVE-2026-64391 has been patched. Fixed versions include 6.12.96, 6.18.39, 7.1.4 and others. If you are running Linux kernel 5.15 or later up to the fix versions, apply the relevant patch for your kernel branch.
Is CVE-2026-64391 actively exploited?

No. CVE-2026-64391 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.