What is CVE-2026-43423?

CVE-2026-43423 is a Medium severity Linux kernel vulnerability with a CVSS score of 5.5 out of 10, classified as a Improper Locking flaw (CWE-667), affecting Linux kernel versions from 6.18.17 onward and patched in 6.18.19 and 6.19.9. CVE-2026-43423 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

What is the CVSS score for CVE-2026-43423?

CVE-2026-43423 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-2026-43423?

Yes, CVE-2026-43423 has been patched. Fixed versions include 6.18.19 and 6.19.9. If you are running Linux kernel 6.18.17 or later up to the fix versions, apply the relevant patch for your kernel branch.

Is CVE-2026-43423 actively exploited?

CVE-2026-43423 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

What is Improper Locking (CWE-667)?

The product does not properly acquire or release a lock, which can lead to unexpected behaviour. See MITRE CWE for full details: https://cwe.mitre.org/data/definitions/667.html

CVE-2026-43423

Medium

In the Linux kernel, the following vulnerability has been resolved: usb: gadget: f_ncm: Fix atomic context locking issue The ncm_set_alt function was holding a mutex to protect against races with configfs, which invokes the might-sleep function inside an atomic context. Remove the struct net_device pointer from the f_ncm_opts structure to eliminate the contention. The connection state is now managed by a new boolean flag to preserve the use-after-free fix from commit 6334b8e4553c ("usb: gadget: f_ncm: Fix UAF ncm object at re-bind after usb ep transport error"). BUG: sleeping function called from invalid context Call Trace: dump_stack_lvl+0x83/0xc0 dump_stack+0x14/0x16 __might_resched+0x389/0x4c0 __might_sleep+0x8e/0x100 ... __mutex_lock+0x6f/0x1740 ... ncm_set_alt+0x209/0xa40 set_config+0x6b6/0xb40 composite_setup+0x734/0x2b40 ...

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

Weakness type

CWE-667

CVE-2026-43423 is a Improper Locking vulnerability

What is Improper Locking?

The product does not properly acquire or release a lock, which can lead to unexpected behaviour. Learn more on MITRE CWE

Affected versions

Linux kernel versions 6.18.17, 6.19.7 and later are affected. Fixed in 6.18.19, 6.19.9 and their respective stable series.

Affected from

≥ 6.18.17 ≥ 6.19.7

Fixed in

✓ 6.18.19 6.18.x ✓ 6.19.9 6.19.x

References

3 total

Kernel Git
https://git.kernel.org/stable/c/0d6c8144ca4d93253de952a5ea0028c19ed7ab68

Patch
Kernel Git
https://git.kernel.org/stable/c/e533a44fb1b337d14f772585b67328bee2e0b5e3

Patch
Kernel Git
https://git.kernel.org/stable/c/e95120b4b95ef1c16d8e94e201ae89f5e59e2612

Patch

Details

CVE ID CVE-2026-43423

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-2026-43423?

CVE-2026-43423 is a Medium severity Linux kernel vulnerability with a CVSS score of 5.5 out of 10 , classified as an Improper Locking flaw (CWE-667) . It affects Linux kernel versions from 6.18.17 onward and has been patched in 6.18.19 and 6.19.9. CVE-2026-43423 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.
What is the CVSS score for CVE-2026-43423?

CVE-2026-43423 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-2026-43423?

Yes. CVE-2026-43423 has been patched. Fixed versions include 6.18.19 and 6.19.9. If you are running Linux kernel 6.18.17 or later up to the fix versions, apply the relevant patch for your kernel branch.
Is CVE-2026-43423 actively exploited?

No. CVE-2026-43423 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.