What is CVE-2026-23139?

CVE-2026-23139 is a Medium severity Linux kernel vulnerability with a CVSS score of 5.5 out of 10, affecting Linux kernel versions from 5.19 onward and patched in 6.1.161, 6.6.121, 6.12.66 and others. CVE-2026-23139 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

What is the CVSS score for CVE-2026-23139?

CVE-2026-23139 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-2026-23139?

Yes, CVE-2026-23139 has been patched. Fixed versions include 6.1.161, 6.6.121, 6.12.66 and others. If you are running Linux kernel 5.19 or later up to the fix versions, apply the relevant patch for your kernel branch.

Is CVE-2026-23139 actively exploited?

CVE-2026-23139 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

CVE-2026-23139

Medium

In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_conncount: update last_gc only when GC has been performed Currently last_gc is being updated everytime a new connection is tracked, that means that it is updated even if a GC wasn't performed. With a sufficiently high packet rate, it is possible to always bypass the GC, causing the list to grow infinitely. Update the last_gc value only when a GC has been actually performed.

Package Linux Kernel

Published 2026-02-14

Last modified 2026-04-03

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 5.19 and later are affected. Fixed in 6.1.161, 6.6.121, 6.12.66, 6.18.6, 6.19 and their respective stable series.

Affected from

≥ 5.19

Fixed in

✓ 6.1.161 6.1.x ✓ 6.6.121 6.6.x ✓ 6.12.66 6.12.x ✓ 6.18.6 6.18.x ✓ 6.19

References

The following references provide additional information about CVE-2026-23139 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/26a82dce2beee39c43c109d9647e16f49cb02a35
Patch
Kernel patch commit
https://git.kernel.org/stable/c/2c7c71113ed6d3e2f3aca4c088f22283016ff34f
Patch
Kernel patch commit
https://git.kernel.org/stable/c/3cd717359e56f82f06cbf8279b47a7d79880c6f3
Patch

7 patch commits total View all on NVD

Details

CVE ID CVE-2026-23139

Severity Medium

CVSS score 5.5 / 10

CVSS version 3.1

Published 2026-02-14

Modified 2026-04-03

KEV No

Patch

Yes

Package linux

Frequently asked questions

What is CVE-2026-23139?

CVE-2026-23139 is a Medium severity Linux kernel vulnerability with a CVSS score of 5.5 out of 10 . It affects Linux kernel versions from 5.19 onward and has been patched in 6.1.161, 6.6.121, 6.12.66 and others. CVE-2026-23139 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.
What is the CVSS score for CVE-2026-23139?

CVE-2026-23139 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-2026-23139?

Yes — CVE-2026-23139 has been patched. Fixed versions include 6.1.161, 6.6.121, 6.12.66 and others. If you are running Linux kernel 5.19 or later up to the fix versions, apply the relevant patch for your kernel branch.
Is CVE-2026-23139 actively exploited?

No — CVE-2026-23139 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.