What is CVE-2026-43491?

CVE-2026-43491 is a Medium severity Linux kernel vulnerability with a CVSS score of 5.5 out of 10, affecting Linux kernel versions from 5.7 onward and patched in 6.6.140, 6.12.86, 6.18.27 and others. CVE-2026-43491 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

What is the CVSS score for CVE-2026-43491?

CVE-2026-43491 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-2026-43491?

Yes, CVE-2026-43491 has been patched. Fixed versions include 6.6.140, 6.12.86, 6.18.27 and others. If you are running Linux kernel 5.7 or later up to the fix versions, apply the relevant patch for your kernel branch.

Is CVE-2026-43491 actively exploited?

CVE-2026-43491 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

CVE-2026-43491

Medium

In the Linux kernel, the following vulnerability has been resolved: net: qrtr: ns: Limit the maximum server registration per node Current code does no bound checking on the number of servers added per node. A malicious client can flood NEW_SERVER messages and exhaust memory. Fix this issue by limiting the maximum number of server registrations to 256 per node. If the NEW_SERVER message is received for an old port, then don't restrict it as it will get replaced. While at it, also rate limit the error messages in the failure path of qrtr_ns_worker(). Note that the limit of 256 is chosen based on the current platform requirements. If requirement changes in the future, this limit can be increased.

Package Linux Kernel

Published 2026-05-19

Last modified 2026-06-26

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 5.7 and later are affected. Fixed in 6.6.140, 6.12.86, 6.18.27, 7.0.4, 7.1 and their respective stable series.

Affected from

≥ 5.7

Fixed in

✓ 6.6.140 6.6.x ✓ 6.12.86 6.12.x ✓ 6.18.27 6.18.x ✓ 7.0.4 7.0.x ✓ 7.1

References

5 total

Kernel Git
https://git.kernel.org/stable/c/35fb4a0c077c5d1049c2628b769e0a1b1e65df0d

Patch
Kernel Git
https://git.kernel.org/stable/c/3efaad55cad1ded429e3a873bfece389058a526b

Patch
Kernel Git
https://git.kernel.org/stable/c/868202aa2adae427060a42d5bd663b4d782ec02c

Patch
Kernel Git
https://git.kernel.org/stable/c/d5ee2ff98322337951c56398e79d51815acbf955

Patch
Kernel Git
https://git.kernel.org/stable/c/e6f6cd501fb54060940a6eb3f4103eeb5e426ae7

Patch

Details

CVE ID CVE-2026-43491

Severity Medium

CVSS score 5.5 / 10

CVSS version 3.1

Published 2026-05-19

Modified 2026-06-26

KEV No

Patch

Yes

Package linux

Frequently asked questions

What is CVE-2026-43491?

CVE-2026-43491 is a Medium severity Linux kernel vulnerability with a CVSS score of 5.5 out of 10 . It affects Linux kernel versions from 5.7 onward and has been patched in 6.6.140, 6.12.86, 6.18.27 and others. CVE-2026-43491 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.
What is the CVSS score for CVE-2026-43491?

CVE-2026-43491 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-2026-43491?

Yes. CVE-2026-43491 has been patched. Fixed versions include 6.6.140, 6.12.86, 6.18.27 and others. If you are running Linux kernel 5.7 or later up to the fix versions, apply the relevant patch for your kernel branch.
Is CVE-2026-43491 actively exploited?

No. CVE-2026-43491 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.