What is CVE-2026-31478?

CVE-2026-31478 is a Critical severity Linux kernel vulnerability with a CVSS score of 9.8 out of 10, affecting Linux kernel versions from 5.15.145 onward and patched in 5.15.203, 6.1.168, 6.6.131 and others. CVE-2026-31478 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

What is the CVSS score for CVE-2026-31478?

CVE-2026-31478 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-2026-31478?

Yes, CVE-2026-31478 has been patched. Fixed versions include 5.15.203, 6.1.168, 6.6.131 and others. If you are running Linux kernel 5.15.145 or later up to the fix versions, apply the relevant patch for your kernel branch.

Is CVE-2026-31478 actively exploited?

CVE-2026-31478 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

CVE-2026-31478

Critical

In the Linux kernel, the following vulnerability has been resolved: ksmbd: replace hardcoded hdr2_len with offsetof() in smb2_calc_max_out_buf_len() After this commit (e2b76ab8b5c9 "ksmbd: add support for read compound"), response buffer management was changed to use dynamic iov array. In the new design, smb2_calc_max_out_buf_len() expects the second argument (hdr2_len) to be the offset of ->Buffer field in the response structure, not a hardcoded magic number. Fix the remaining call sites to use the correct offsetof() value.

Package Linux Kernel

Published 2026-04-22

Last modified 2026-04-27

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

Affected versions

Linux kernel versions 5.15.145, 6.1.71, 6.6 and later are affected. Fixed in 5.15.203, 6.1.168, 6.6.131, 6.12.80, 6.18.21, 6.19.11, 7.0 and their respective stable series.

Affected from

≥ 5.15.145 ≥ 6.1.71 ≥ 6.6

Fixed in

✓ 5.15.203 5.15.x ✓ 6.1.168 6.1.x ✓ 6.6.131 6.6.x ✓ 6.12.80 6.12.x ✓ 6.18.21 6.18.x ✓ 6.19.11 6.19.x ✓ 7.0

References

The following references provide additional information about CVE-2026-31478 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/0e55f63dd08f09651d39e1b709a91705a8a0ddcb
Patch
Kernel patch commit
https://git.kernel.org/stable/c/4cb537ae4f37d7d0f617815ed4bed7173fb50861
Patch
Kernel patch commit
https://git.kernel.org/stable/c/6aef1765d6807e0f027cd87f6ac973eb0879a46d
Patch

7 patch commits total View all on NVD

Details

CVE ID CVE-2026-31478

Severity Critical

CVSS score 9.8 / 10

CVSS version 3.1

Published 2026-04-22

Modified 2026-04-27

KEV No

Patch

Yes

Package linux

Frequently asked questions

What is CVE-2026-31478?

CVE-2026-31478 is a Critical severity Linux kernel vulnerability with a CVSS score of 9.8 out of 10 . It affects Linux kernel versions from 5.15.145 onward and has been patched in 5.15.203, 6.1.168, 6.6.131 and others. CVE-2026-31478 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.
What is the CVSS score for CVE-2026-31478?

CVE-2026-31478 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-2026-31478?

Yes — CVE-2026-31478 has been patched. Fixed versions include 5.15.203, 6.1.168, 6.6.131 and others. If you are running Linux kernel 5.15.145 or later up to the fix versions, apply the relevant patch for your kernel branch.
Is CVE-2026-31478 actively exploited?

No — CVE-2026-31478 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.