What is CVE-2026-23403?

CVE-2026-23403 is a Medium severity Linux kernel vulnerability with a CVSS score of 5.5 out of 10, classified as a Memory Leak flaw (CWE-401), affecting Linux kernel versions from 3.12 onward and patched in 5.10.253, 5.15.203, 6.1.169 and others. CVE-2026-23403 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

What is the CVSS score for CVE-2026-23403?

CVE-2026-23403 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-2026-23403?

Yes, CVE-2026-23403 has been patched. Fixed versions include 5.10.253, 5.15.203, 6.1.169 and others. If you are running Linux kernel 3.12 or later up to the fix versions, apply the relevant patch for your kernel branch.

Is CVE-2026-23403 actively exploited?

CVE-2026-23403 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

What is Memory Leak (CWE-401)?

The product does not release memory after use, causing gradual resource exhaustion. See MITRE CWE for full details: https://cwe.mitre.org/data/definitions/401.html

CVE-2026-23403

Medium

In the Linux kernel, the following vulnerability has been resolved: apparmor: fix memory leak in verify_header The function sets `*ns = NULL` on every call, leaking the namespace string allocated in previous iterations when multiple profiles are unpacked. This also breaks namespace consistency checking since *ns is always NULL when the comparison is made. Remove the incorrect assignment. The caller (aa_unpack) initializes *ns to NULL once before the loop, which is sufficient.

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

Weakness type

CWE-401

CVE-2026-23403 is a Memory Leak vulnerability

What is Memory Leak?

The product does not release memory after use, causing gradual resource exhaustion. Learn more on MITRE CWE

Affected versions

Linux kernel versions 3.12 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

≥ 3.12

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

8 total

Kernel Git
https://git.kernel.org/stable/c/42fd831abfc15d0643c14688f0522556b347e7e6

Patch
Kernel Git
https://git.kernel.org/stable/c/4f0889f2df1ab99224a5e1ac4e20437eea5fe38e

Patch
Kernel Git
https://git.kernel.org/stable/c/663ce34786e759ebcbeb3060685c20bcc886d51a

Patch
Kernel Git
https://git.kernel.org/stable/c/6b79abcb3c985e153fcf9d395e1d4336081aabc2

Patch
Kernel Git
https://git.kernel.org/stable/c/786e2c2a87d9c505f33321d1fd23a176aa8ddeb1

Patch

Showing 5 of 8 references View all on NVD

Details

CVE ID CVE-2026-23403

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-2026-23403?

CVE-2026-23403 is a Medium severity Linux kernel vulnerability with a CVSS score of 5.5 out of 10 , classified as a Memory Leak flaw (CWE-401) . It affects Linux kernel versions from 3.12 onward and has been patched in 5.10.253, 5.15.203, 6.1.169 and others. CVE-2026-23403 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.
What is the CVSS score for CVE-2026-23403?

CVE-2026-23403 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-2026-23403?

Yes. CVE-2026-23403 has been patched. Fixed versions include 5.10.253, 5.15.203, 6.1.169 and others. If you are running Linux kernel 3.12 or later up to the fix versions, apply the relevant patch for your kernel branch.
Is CVE-2026-23403 actively exploited?

No. CVE-2026-23403 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.