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). 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?

No patch is currently available for CVE-2026-23403. Monitor the NIST NVD and your Linux distribution's security advisories for updates.

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

Awaiting data

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

References

The following references provide additional information about CVE-2026-23403 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/42fd831abfc15d0643c14688f0522556b347e7e6
Patch
Kernel patch commit
https://git.kernel.org/stable/c/4f0889f2df1ab99224a5e1ac4e20437eea5fe38e
Patch
Kernel patch commit
https://git.kernel.org/stable/c/663ce34786e759ebcbeb3060685c20bcc886d51a
Patch

8 patch commits total 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 Awaiting data

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) . 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?

No patch is currently available for CVE-2026-23403. Monitor the NIST NVD and your Linux distribution's security advisories for updates.
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.
What is Memory Leak (CWE-401)?

The product does not release memory after use, causing gradual resource exhaustion. View CWE-401 on MITRE CWE →