What is CVE-2026-31704?

CVE-2026-31704 is a Medium severity Linux kernel vulnerability with a CVSS score of 5.5 out of 10, affecting Linux kernel versions from 5.15 onward and patched in 6.1.175, 6.6.136, 6.12.84 and others. CVE-2026-31704 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

What is the CVSS score for CVE-2026-31704?

CVE-2026-31704 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-2026-31704?

Yes, CVE-2026-31704 has been patched. Fixed versions include 6.1.175, 6.6.136, 6.12.84 and others. If you are running Linux kernel 5.15 or later up to the fix versions, apply the relevant patch for your kernel branch.

Is CVE-2026-31704 actively exploited?

CVE-2026-31704 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

CVE-2026-31704

Medium

In the Linux kernel, the following vulnerability has been resolved: ksmbd: use check_add_overflow() to prevent u16 DACL size overflow set_posix_acl_entries_dacl() and set_ntacl_dacl() accumulate ACE sizes in u16 variables. When a file has many POSIX ACL entries, the accumulated size can wrap past 65535, causing the pointer arithmetic (char *)pndace + *size to land within already-written ACEs. Subsequent writes then overwrite earlier entries, and pndacl->size gets a truncated value. Use check_add_overflow() at each accumulation point to detect the wrap before it corrupts the buffer, consistent with existing check_mul_overflow() usage elsewhere in smbacl.c.

Package Linux Kernel

Published 2026-05-01

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 5.15 and later are affected. Fixed in 6.1.175, 6.6.136, 6.12.84, 6.18.25, 7.0.2, 7.1-rc1 and their respective stable series.

Affected from

≥ 5.15

Fixed in

✓ 6.1.175 6.1.x ✓ 6.6.136 6.6.x ✓ 6.12.84 6.12.x ✓ 6.18.25 6.18.x ✓ 7.0.2 7.0.x ✓ 7.1-rc1

References

The following references provide additional information about CVE-2026-31704 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/299f962c0b02d048fb45d248b4da493d03f3175d
Patch
Kernel patch commit
https://git.kernel.org/stable/c/41e53a773db6342ac9a689ee5ba635c31744c9f0
Patch
Kernel patch commit
https://git.kernel.org/stable/c/5e7b8f3c539d69b2ed5f2408e2f75e68ce7eef43
Patch

6 patch commits total View all on NVD

Details

CVE ID CVE-2026-31704

Severity Medium

CVSS score 5.5 / 10

CVSS version 3.1

Published 2026-05-01

Modified 2026-06-01

KEV No

Patch

Yes

Package linux

Frequently asked questions

What is CVE-2026-31704?

CVE-2026-31704 is a Medium severity Linux kernel vulnerability with a CVSS score of 5.5 out of 10 . It affects Linux kernel versions from 5.15 onward and has been patched in 6.1.175, 6.6.136, 6.12.84 and others. CVE-2026-31704 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.
What is the CVSS score for CVE-2026-31704?

CVE-2026-31704 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-2026-31704?

Yes — CVE-2026-31704 has been patched. Fixed versions include 6.1.175, 6.6.136, 6.12.84 and others. If you are running Linux kernel 5.15 or later up to the fix versions, apply the relevant patch for your kernel branch.
Is CVE-2026-31704 actively exploited?

No — CVE-2026-31704 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.