What is CVE-2026-31609?

CVE-2026-31609 is a Critical severity Linux kernel vulnerability with a CVSS score of 9.8 out of 10, affecting Linux kernel versions from 6.18.11 onward and patched in 6.18.24, 6.19.14, 7.0.1 and others. CVE-2026-31609 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

What is the CVSS score for CVE-2026-31609?

CVE-2026-31609 has a CVSS score of 9.8 out of 10, rated Critical severity. The vector string is CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

Is there a patch available for CVE-2026-31609?

Yes, CVE-2026-31609 has been patched. Fixed versions include 6.18.24, 6.19.14, 7.0.1 and others. If you are running Linux kernel 6.18.11 or later up to the fix versions, apply the relevant patch for your kernel branch.

Is CVE-2026-31609 actively exploited?

CVE-2026-31609 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

CVE-2026-31609

Critical

In the Linux kernel, the following vulnerability has been resolved: smb: client: avoid double-free in smbd_free_send_io() after smbd_send_batch_flush() smbd_send_batch_flush() already calls smbd_free_send_io(), so we should not call it again after smbd_post_send() moved it to the batch list.

Package Linux Kernel

Published 2026-04-24

Last modified 2026-04-29

CVSS version 3.1

Patch available

Yes

CVSS 3.1 score

9.8

out of 10

Critical

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Vector string

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

Weakness type

CWE-415

CVE-2026-31609 is classified as CWE-415

See CWE-415 on MITRE CWE for full details on this weakness type.

Affected versions

Linux kernel versions 6.18.11, 6.19.1, 7.0 and later are affected. Fixed in 6.18.24, 6.19.14, 7.0.1, 7.1-rc1 and their respective stable series.

Affected from

≥ 6.18.11 ≥ 6.19.1 ≥ 7.0

Fixed in

✓ 6.18.24 6.18.x ✓ 6.19.14 6.19.x ✓ 7.0.1 7.0.x ✓ 7.1-rc1

References

The following references provide additional information about CVE-2026-31609 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/22b7c1c619d808aec4cad3dc42103345e370d107
Patch
Kernel patch commit
https://git.kernel.org/stable/c/27b7c3e916218b5eb2ee350211140e961bfc49be
Patch
Kernel patch commit
https://git.kernel.org/stable/c/a9940dcbe5cb92482c04efc7341039ddf7dbf607
Patch

4 patch commits total View all on NVD

Details

CVE ID CVE-2026-31609

Severity Critical

CVSS score 9.8 / 10

CVSS version 3.1

Published 2026-04-24

Modified 2026-04-29

KEV No

Patch

Yes

Package linux

Frequently asked questions

What is CVE-2026-31609?

CVE-2026-31609 is a Critical severity Linux kernel vulnerability with a CVSS score of 9.8 out of 10 . It affects Linux kernel versions from 6.18.11 onward and has been patched in 6.18.24, 6.19.14, 7.0.1 and others. CVE-2026-31609 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.
What is the CVSS score for CVE-2026-31609?

CVE-2026-31609 has a CVSS score of 9.8 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:H/I:H/A:H.
Is there a patch available for CVE-2026-31609?

Yes — CVE-2026-31609 has been patched. Fixed versions include 6.18.24, 6.19.14, 7.0.1 and others. If you are running Linux kernel 6.18.11 or later up to the fix versions, apply the relevant patch for your kernel branch.
Is CVE-2026-31609 actively exploited?

No — CVE-2026-31609 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.