What is CVE-2026-31664?

CVE-2026-31664 is a Medium severity Linux kernel vulnerability with a CVSS score of 5.5 out of 10, affecting Linux kernel versions from 2.6.12 onward and patched in 5.10.258, 5.15.209, 6.1.169 and others. CVE-2026-31664 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

What is the CVSS score for CVE-2026-31664?

CVE-2026-31664 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-2026-31664?

Yes, CVE-2026-31664 has been patched. Fixed versions include 5.10.258, 5.15.209, 6.1.169 and others. If you are running Linux kernel 2.6.12 or later up to the fix versions, apply the relevant patch for your kernel branch.

Is CVE-2026-31664 actively exploited?

CVE-2026-31664 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

CVE-2026-31664

Medium

In the Linux kernel, the following vulnerability has been resolved: xfrm: clear trailing padding in build_polexpire() build_expire() clears the trailing padding bytes of struct xfrm_user_expire after setting the hard field via memset_after(), but the analogous function build_polexpire() does not do this for struct xfrm_user_polexpire. The padding bytes after the __u8 hard field are left uninitialized from the heap allocation, and are then sent to userspace via netlink multicast to XFRMNLGRP_EXPIRE listeners, leaking kernel heap memory contents. Add the missing memset_after() call, matching build_expire().

Package Linux Kernel

Published 2026-04-24

Last modified 2026-06-01

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 2.6.12 and later are affected. Fixed in 5.10.258, 5.15.209, 6.1.169, 6.6.135, 6.12.82, 6.18.23, 6.19.13, 7.0 and their respective stable series.

Affected from

≥ 2.6.12

Fixed in

✓ 5.10.258 5.10.x ✓ 5.15.209 5.15.x ✓ 6.1.169 6.1.x ✓ 6.6.135 6.6.x ✓ 6.12.82 6.12.x ✓ 6.18.23 6.18.x ✓ 6.19.13 6.19.x ✓ 7.0

References

The following references provide additional information about CVE-2026-31664 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/71a98248c63c535eaa4d4c22f099b68d902006d0
Patch
Kernel patch commit
https://git.kernel.org/stable/c/a5127501c8d30b5728791b1e340284ca5c9cc4bd
Patch
Kernel patch commit
https://git.kernel.org/stable/c/ac6985903db047eaff54db929e4bf6b06782788e
Patch

8 patch commits total View all on NVD

Details

CVE ID CVE-2026-31664

Severity Medium

CVSS score 5.5 / 10

CVSS version 3.1

Published 2026-04-24

Modified 2026-06-01

KEV No

Patch

Yes

Package linux

Frequently asked questions

What is CVE-2026-31664?

CVE-2026-31664 is a Medium severity Linux kernel vulnerability with a CVSS score of 5.5 out of 10 . It affects Linux kernel versions from 2.6.12 onward and has been patched in 5.10.258, 5.15.209, 6.1.169 and others. CVE-2026-31664 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.
What is the CVSS score for CVE-2026-31664?

CVE-2026-31664 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-2026-31664?

Yes — CVE-2026-31664 has been patched. Fixed versions include 5.10.258, 5.15.209, 6.1.169 and others. If you are running Linux kernel 2.6.12 or later up to the fix versions, apply the relevant patch for your kernel branch.
Is CVE-2026-31664 actively exploited?

No — CVE-2026-31664 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.