What is CVE-2026-43403?

CVE-2026-43403 is a High severity Linux kernel vulnerability with a CVSS score of 8.8 out of 10, affecting Linux kernel versions from 6.12 onward and patched in 6.12.78, 6.18.20, 6.19.9 and others. CVE-2026-43403 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

What is the CVSS score for CVE-2026-43403?

CVE-2026-43403 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-2026-43403?

Yes, CVE-2026-43403 has been patched. Fixed versions include 6.12.78, 6.18.20, 6.19.9 and others. If you are running Linux kernel 6.12 or later up to the fix versions, apply the relevant patch for your kernel branch.

Is CVE-2026-43403 actively exploited?

CVE-2026-43403 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

CVE-2026-43403

High

In the Linux kernel, the following vulnerability has been resolved: nsfs: tighten permission checks for ns iteration ioctls 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 2026-05-21

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 6.12 and later are affected. Fixed in 6.12.78, 6.18.20, 6.19.9, 7.0 and their respective stable series.

Affected from

≥ 6.12

Fixed in

✓ 6.12.78 6.12.x ✓ 6.18.20 6.18.x ✓ 6.19.9 6.19.x ✓ 7.0

References

The following references provide additional information about CVE-2026-43403 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/0ad650e60150eda789deca5e78a6a09d26bf8fc9
Patch
Kernel patch commit
https://git.kernel.org/stable/c/2f3dea284c761c890d676f77d5e55c0c496b4ef4
Patch
Kernel patch commit
https://git.kernel.org/stable/c/3376b345df155ca36d8611857b41ff7d5183fc38
Patch

4 patch commits total View all on NVD

Details

CVE ID CVE-2026-43403

Severity High

CVSS score 8.8 / 10

CVSS version 3.1

Published 2026-05-08

Modified 2026-05-21

KEV No

Patch

Yes

Package linux

Frequently asked questions

What is CVE-2026-43403?

CVE-2026-43403 is a High severity Linux kernel vulnerability with a CVSS score of 8.8 out of 10 . It affects Linux kernel versions from 6.12 onward and has been patched in 6.12.78, 6.18.20, 6.19.9 and others. CVE-2026-43403 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.
What is the CVSS score for CVE-2026-43403?

CVE-2026-43403 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-2026-43403?

Yes — CVE-2026-43403 has been patched. Fixed versions include 6.12.78, 6.18.20, 6.19.9 and others. If you are running Linux kernel 6.12 or later up to the fix versions, apply the relevant patch for your kernel branch.
Is CVE-2026-43403 actively exploited?

No — CVE-2026-43403 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.