What is CVE-2026-43418?

CVE-2026-43418 is a Medium severity Linux kernel vulnerability with a CVSS score of 5.5 out of 10, affecting Linux kernel versions from 6.19 onward and patched in 6.19.9 and 7.0. CVE-2026-43418 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

What is the CVSS score for CVE-2026-43418?

CVE-2026-43418 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-2026-43418?

Yes, CVE-2026-43418 has been patched. Fixed versions include 6.19.9 and 7.0. If you are running Linux kernel 6.19 or later up to the fix versions, apply the relevant patch for your kernel branch.

Is CVE-2026-43418 actively exploited?

CVE-2026-43418 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

CVE-2026-43418

Medium

In the Linux kernel, the following vulnerability has been resolved: sched/mmcid: Prevent CID stalls due to concurrent forks A newly forked task is accounted as MMCID user before the task is visible in the process' thread list and the global task list. This creates the following problem: CPU1 CPU2 fork() sched_mm_cid_fork(tnew1) tnew1->mm.mm_cid_users++; tnew1->mm_cid.cid = getcid() -> preemption fork() sched_mm_cid_fork(tnew2) tnew2->mm.mm_cid_users++; // Reaches the per CPU threshold mm_cid_fixup_tasks_to_cpus() for_each_other(current, p) .... As tnew1 is not visible yet, this fails to fix up the already allocated CID of tnew1. As a consequence a subsequent schedule in might fail to acquire a (transitional) CID and the machine stalls. Move the invocation of sched_mm_cid_fork() after the new task becomes visible in the thread and the task list to prevent this. This also makes it symmetrical vs. exit() where the task is removed as CID user before the task is removed from the thread and task lists.

Package Linux Kernel

Published 2026-05-08

Last modified 2026-05-22

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 6.19 and later are affected. Fixed in 6.19.9, 7.0 and their respective stable series.

Affected from

≥ 6.19

Fixed in

✓ 6.19.9 6.19.x ✓ 7.0

References

The following references provide additional information about CVE-2026-43418 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/b2e48c429ec54715d16fefa719dd2fbded2e65be
Patch
Kernel patch commit
https://git.kernel.org/stable/c/f0189d49282e0458f3a737bd486c1ec048148f66
Patch

Details

CVE ID CVE-2026-43418

Severity Medium

CVSS score 5.5 / 10

CVSS version 3.1

Published 2026-05-08

Modified 2026-05-22

KEV No

Patch

Yes

Package linux

Frequently asked questions

What is CVE-2026-43418?

CVE-2026-43418 is a Medium severity Linux kernel vulnerability with a CVSS score of 5.5 out of 10 . It affects Linux kernel versions from 6.19 onward and has been patched in 6.19.9 and 7.0. CVE-2026-43418 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.
What is the CVSS score for CVE-2026-43418?

CVE-2026-43418 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-2026-43418?

Yes — CVE-2026-43418 has been patched. Fixed versions include 6.19.9 and 7.0. If you are running Linux kernel 6.19 or later up to the fix versions, apply the relevant patch for your kernel branch.
Is CVE-2026-43418 actively exploited?

No — CVE-2026-43418 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.