What is CVE-2026-23405?

CVE-2026-23405 is a Medium severity Linux kernel vulnerability with a CVSS score of 5.5 out of 10, affecting Linux kernel versions from 2.6.36 onward and patched in 5.10.253, 5.15.203, 6.1.169 and others. CVE-2026-23405 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

What is the CVSS score for CVE-2026-23405?

CVE-2026-23405 has a CVSS score of 5.5 out of 10, rated Medium severity. The vector string is CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H.

Is there a patch available for CVE-2026-23405?

Yes, CVE-2026-23405 has been patched. Fixed versions include 5.10.253, 5.15.203, 6.1.169 and others. If you are running Linux kernel 2.6.36 or later up to the fix versions, apply the relevant patch for your kernel branch.

Is CVE-2026-23405 actively exploited?

CVE-2026-23405 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

CVE-2026-23405

Medium

In the Linux kernel, the following vulnerability has been resolved: apparmor: fix: limit the number of levels of policy namespaces Currently the number of policy namespaces is not bounded relying on the user namespace limit. However policy namespaces aren't strictly tied to user namespaces and it is possible to create them and nest them arbitrarily deep which can be used to exhaust system resource. Hard cap policy namespaces to the same depth as user namespaces.

Package Linux Kernel

Published 2026-04-01

Last modified 2026-04-24

CVSS version 3.1

Patch available

Yes

CVSS 3.1 score

5.5

out of 10

Medium

Attack Vector

Local

Attack Complexity

Low

Privileges Required

Low

User Interaction

None

Scope

Unchanged

Confidentiality

Low

Integrity

None

Availability

High

Vector string

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

Affected versions

Linux kernel versions 2.6.36 and later are affected. Fixed in 5.10.253, 5.15.203, 6.1.169, 6.6.130, 6.12.77, 6.18.18, 6.19.8, 7.0 and their respective stable series.

Affected from

≥ 2.6.36

Fixed in

✓ 5.10.253 5.10.x ✓ 5.15.203 5.15.x ✓ 6.1.169 6.1.x ✓ 6.6.130 6.6.x ✓ 6.12.77 6.12.x ✓ 6.18.18 6.18.x ✓ 6.19.8 6.19.x ✓ 7.0

References

The following references provide additional information about CVE-2026-23405 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/306039414932c80f8420695a24d4fe10c84ccfb2
Patch
Kernel patch commit
https://git.kernel.org/stable/c/3f8699b3ee0c04b4b9bc27b82cd89a40e81e1d2e
Patch
Kernel patch commit
https://git.kernel.org/stable/c/6b396cc2f0365e684fc1d3547d18ef79fcee225d
Patch

8 patch commits total View all on NVD

Details

CVE ID CVE-2026-23405

Severity Medium

CVSS score 5.5 / 10

CVSS version 3.1

Published 2026-04-01

Modified 2026-04-24

KEV No

Patch

Yes

Package linux

Frequently asked questions

What is CVE-2026-23405?

CVE-2026-23405 is a Medium severity Linux kernel vulnerability with a CVSS score of 5.5 out of 10 . It affects Linux kernel versions from 2.6.36 onward and has been patched in 5.10.253, 5.15.203, 6.1.169 and others. CVE-2026-23405 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.
What is the CVSS score for CVE-2026-23405?

CVE-2026-23405 has a CVSS score of 5.5 out of 10, rated Medium severity (CVSS 3.1). The vector string is CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H.
Is there a patch available for CVE-2026-23405?

Yes — CVE-2026-23405 has been patched. Fixed versions include 5.10.253, 5.15.203, 6.1.169 and others. If you are running Linux kernel 2.6.36 or later up to the fix versions, apply the relevant patch for your kernel branch.
Is CVE-2026-23405 actively exploited?

No — CVE-2026-23405 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.