What is CVE-2026-43383?

CVE-2026-43383 is a Critical severity Linux kernel vulnerability with a CVSS score of 9.4 out of 10, affecting Linux kernel versions from 2.6.20 onward and patched in 5.10.253, 6.1.167, 6.6.130 and others. CVE-2026-43383 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

What is the CVSS score for CVE-2026-43383?

CVE-2026-43383 has a CVSS score of 9.4 out of 10, rated Critical severity. The vector string is CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:H.

Is there a patch available for CVE-2026-43383?

Yes, CVE-2026-43383 has been patched. Fixed versions include 5.10.253, 6.1.167, 6.6.130 and others. If you are running Linux kernel 2.6.20 or later up to the fix versions, apply the relevant patch for your kernel branch.

Is CVE-2026-43383 actively exploited?

CVE-2026-43383 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

CVE-2026-43383

Critical

In the Linux kernel, the following vulnerability has been resolved: net/tcp-md5: Fix MAC comparison to be constant-time To prevent timing attacks, MACs need to be compared in constant time. Use the appropriate helper function for this.

Package Linux Kernel

Published 2026-05-08

Last modified 2026-05-26

CVSS version 3.1

Patch available

Yes

CVSS 3.1 score

9.4

out of 10

Critical

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

Low

Integrity

High

Availability

High

Vector string

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

Affected versions

Linux kernel versions 2.6.20 and later are affected. Fixed in 5.10.253, 6.1.167, 6.6.130, 6.12.78, 6.18.19, 6.19.9, 7.0 and their respective stable series.

Affected from

≥ 2.6.20

Fixed in

✓ 5.10.253 5.10.x ✓ 6.1.167 6.1.x ✓ 6.6.130 6.6.x ✓ 6.12.78 6.12.x ✓ 6.18.19 6.18.x ✓ 6.19.9 6.19.x ✓ 7.0

References

The following references provide additional information about CVE-2026-43383 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/02669e2a4d207068edce7e8b5fafd85822018ce6
Patch
Kernel patch commit
https://git.kernel.org/stable/c/345a9530756528d7ca407663d659c3c40e75c3dd
Patch
Kernel patch commit
https://git.kernel.org/stable/c/46d0d6f50dab706637f4c18a470aac20a21900d3
Patch

7 patch commits total View all on NVD

Details

CVE ID CVE-2026-43383

Severity Critical

CVSS score 9.4 / 10

CVSS version 3.1

Published 2026-05-08

Modified 2026-05-26

KEV No

Patch

Yes

Package linux

Frequently asked questions

What is CVE-2026-43383?

CVE-2026-43383 is a Critical severity Linux kernel vulnerability with a CVSS score of 9.4 out of 10 . It affects Linux kernel versions from 2.6.20 onward and has been patched in 5.10.253, 6.1.167, 6.6.130 and others. CVE-2026-43383 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.
What is the CVSS score for CVE-2026-43383?

CVE-2026-43383 has a CVSS score of 9.4 out of 10, rated Critical severity (CVSS 3.1). The vector string is CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:H.
Is there a patch available for CVE-2026-43383?

Yes — CVE-2026-43383 has been patched. Fixed versions include 5.10.253, 6.1.167, 6.6.130 and others. If you are running Linux kernel 2.6.20 or later up to the fix versions, apply the relevant patch for your kernel branch.
Is CVE-2026-43383 actively exploited?

No — CVE-2026-43383 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.