What is CVE-2026-43391?

CVE-2026-43391 is a High severity Linux kernel vulnerability with a CVSS score of 8.8 out of 10, affecting Linux kernel versions from 6.18 onward and patched in 6.19.9 and 7.0. CVE-2026-43391 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

What is the CVSS score for CVE-2026-43391?

CVE-2026-43391 has a CVSS score of 8.8 out of 10, rated High severity. The vector string is CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H.

Is there a patch available for CVE-2026-43391?

Yes, CVE-2026-43391 has been patched. Fixed versions include 6.19.9 and 7.0. If you are running Linux kernel 6.18 or later up to the fix versions, apply the relevant patch for your kernel branch.

Is CVE-2026-43391 actively exploited?

CVE-2026-43391 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

CVE-2026-43391

High

In the Linux kernel, the following vulnerability has been resolved: nsfs: tighten permission checks for handle opening Even privileged services should not necessarily be able to see other privileged service's namespaces so they can't leak information to each other. Use may_see_all_namespaces() helper that centralizes this policy until the nstree adapts.

Package Linux Kernel

Published 2026-05-08

Last modified 2026-05-26

CVSS version 3.1

Patch available

Yes

CVSS 3.1 score

8.8

out of 10

High

Attack Vector

Local

Attack Complexity

Low

Privileges Required

Low

User Interaction

None

Scope

Changed

Confidentiality

High

Integrity

High

Availability

High

Vector string

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

Affected versions

Linux kernel versions 6.18 and later are affected. Fixed in 6.19.9, 7.0 and their respective stable series.

Affected from

≥ 6.18

Fixed in

✓ 6.19.9 6.19.x ✓ 7.0

References

The following references provide additional information about CVE-2026-43391 including vendor advisories, patch commits, exploit details, and third-party analysis. Links are sourced from the NIST NVD database.

Kernel patch commit
https://git.kernel.org/stable/c/1797ee11451f1b2be69863a9f5bd43b948813fdf
Patch
Kernel patch commit
https://git.kernel.org/stable/c/d2324a9317f00013facb0ba00b00440e19d2af5e
Patch

Details

CVE ID CVE-2026-43391

Severity High

CVSS score 8.8 / 10

CVSS version 3.1

Published 2026-05-08

Modified 2026-05-26

KEV No

Patch

Yes

Package linux

Frequently asked questions

What is CVE-2026-43391?

CVE-2026-43391 is a High severity Linux kernel vulnerability with a CVSS score of 8.8 out of 10 . It affects Linux kernel versions from 6.18 onward and has been patched in 6.19.9 and 7.0. CVE-2026-43391 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.
What is the CVSS score for CVE-2026-43391?

CVE-2026-43391 has a CVSS score of 8.8 out of 10, rated High severity (CVSS 3.1). The vector string is CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H.
Is there a patch available for CVE-2026-43391?

Yes — CVE-2026-43391 has been patched. Fixed versions include 6.19.9 and 7.0. If you are running Linux kernel 6.18 or later up to the fix versions, apply the relevant patch for your kernel branch.
Is CVE-2026-43391 actively exploited?

No — CVE-2026-43391 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.