What is CVE-2026-43040?

CVE-2026-43040 is a High severity Linux kernel vulnerability with a CVSS score of 7.1 out of 10, affecting Linux kernel versions from 2.6.24 onward and patched in 5.10.253, 5.15.203, 6.1.168 and others. CVE-2026-43040 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

What is the CVSS score for CVE-2026-43040?

CVE-2026-43040 has a CVSS score of 7.1 out of 10, rated High severity. The vector string is CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H.

Is there a patch available for CVE-2026-43040?

Yes, CVE-2026-43040 has been patched. Fixed versions include 5.10.253, 5.15.203, 6.1.168 and others. If you are running Linux kernel 2.6.24 or later up to the fix versions, apply the relevant patch for your kernel branch.

Is CVE-2026-43040 actively exploited?

CVE-2026-43040 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

CVE-2026-43040

High

In the Linux kernel, the following vulnerability has been resolved: net: ipv6: ndisc: fix ndisc_ra_useropt to initialize nduseropt_padX fields to zero to prevent an info-leak When processing Router Advertisements with user options the kernel builds an RTM_NEWNDUSEROPT netlink message. The nduseroptmsg struct has three padding fields that are never zeroed and can leak kernel data The fix is simple, just zeroes the padding fields.

Package Linux Kernel

Published 2026-05-01

Last modified 2026-05-08

CVSS version 3.1

Patch available

Yes

CVSS 3.1 score

7.1

out of 10

High

Attack Vector

Local

Attack Complexity

Low

Privileges Required

Low

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

None

Availability

High

Vector string

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

Weakness type

CWE-909

CVE-2026-43040 is classified as CWE-909

See CWE-909 on MITRE CWE for full details on this weakness type.

Affected versions

Linux kernel versions 2.6.24 and later are affected. Fixed in 5.10.253, 5.15.203, 6.1.168, 6.6.134, 6.12.81, 6.18.22, 6.19.12, 7.0 and their respective stable series.

Affected from

≥ 2.6.24

Fixed in

✓ 5.10.253 5.10.x ✓ 5.15.203 5.15.x ✓ 6.1.168 6.1.x ✓ 6.6.134 6.6.x ✓ 6.12.81 6.12.x ✓ 6.18.22 6.18.x ✓ 6.19.12 6.19.x ✓ 7.0

References

The following references provide additional information about CVE-2026-43040 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/11d7fe97421cfc81549940c20ed5ac9472d6db05
Patch
Kernel patch commit
https://git.kernel.org/stable/c/1da9023f6b071a38e5430ffbce4b70b2b1ac4f9c
Patch
Kernel patch commit
https://git.kernel.org/stable/c/2fe4d0ba690a69ad6ae9f7ab9bdc96e02610b648
Patch

8 patch commits total View all on NVD

Details

CVE ID CVE-2026-43040

Severity High

CVSS score 7.1 / 10

CVSS version 3.1

Published 2026-05-01

Modified 2026-05-08

KEV No

Patch

Yes

Package linux

Frequently asked questions

What is CVE-2026-43040?

CVE-2026-43040 is a High severity Linux kernel vulnerability with a CVSS score of 7.1 out of 10 . It affects Linux kernel versions from 2.6.24 onward and has been patched in 5.10.253, 5.15.203, 6.1.168 and others. CVE-2026-43040 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.
What is the CVSS score for CVE-2026-43040?

CVE-2026-43040 has a CVSS score of 7.1 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:U/C:H/I:N/A:H.
Is there a patch available for CVE-2026-43040?

Yes — CVE-2026-43040 has been patched. Fixed versions include 5.10.253, 5.15.203, 6.1.168 and others. If you are running Linux kernel 2.6.24 or later up to the fix versions, apply the relevant patch for your kernel branch.
Is CVE-2026-43040 actively exploited?

No — CVE-2026-43040 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.