What is CVE-2025-39858?

CVE-2025-39858 is a Medium severity Linux kernel vulnerability with a CVSS score of 5.5 out of 10, classified as a NULL Pointer Dereference flaw (CWE-476), affecting Linux kernel versions from 6.15 onward and patched in 6.16.6 and 6.17. CVE-2025-39858 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

What is the CVSS score for CVE-2025-39858?

CVE-2025-39858 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-2025-39858?

Yes, CVE-2025-39858 has been patched. Fixed versions include 6.16.6 and 6.17. If you are running Linux kernel 6.15 or later up to the fix versions, apply the relevant patch for your kernel branch.

Is CVE-2025-39858 actively exploited?

CVE-2025-39858 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

What is NULL Pointer Dereference (CWE-476)?

The product dereferences a pointer that it expects to be valid but is NULL, typically causing a crash. See MITRE CWE for full details: https://cwe.mitre.org/data/definitions/476.html

CVE-2025-39858

Medium

In the Linux kernel, the following vulnerability has been resolved: eth: mlx4: Fix IS_ERR() vs NULL check bug in mlx4_en_create_rx_ring Replace NULL check with IS_ERR() check after calling page_pool_create() since this function returns error pointers (ERR_PTR). Using NULL check could lead to invalid pointer dereference.

Package Linux Kernel

Published 2025-09-19

Last modified 2026-01-14

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

Weakness type

CWE-476

CVE-2025-39858 is a NULL Pointer Dereference vulnerability

What is NULL Pointer Dereference?

The product dereferences a pointer that it expects to be valid but is NULL, typically causing a crash. Learn more on MITRE CWE

Affected versions

Linux kernel versions 6.15 and later are affected. Fixed in 6.16.6, 6.17 and their respective stable series.

Affected from

≥ 6.15

Fixed in

✓ 6.16.6 6.16.x ✓ 6.17

References

The following references provide additional information about CVE-2025-39858 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/7b77d8841a98a9f45c8a615222c698df8dec581c
Patch
Kernel patch commit
https://git.kernel.org/stable/c/e580beaf43d563aaf457f1c7f934002355ebfe7b
Patch

Details

CVE ID CVE-2025-39858

Severity Medium

CVSS score 5.5 / 10

CVSS version 3.1

Published 2025-09-19

Modified 2026-01-14

KEV No

Patch

Yes

Package linux

Frequently asked questions

What is CVE-2025-39858?

CVE-2025-39858 is a Medium severity Linux kernel vulnerability with a CVSS score of 5.5 out of 10 , classified as a NULL Pointer Dereference flaw (CWE-476) . It affects Linux kernel versions from 6.15 onward and has been patched in 6.16.6 and 6.17. CVE-2025-39858 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.
What is the CVSS score for CVE-2025-39858?

CVE-2025-39858 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-2025-39858?

Yes — CVE-2025-39858 has been patched. Fixed versions include 6.16.6 and 6.17. If you are running Linux kernel 6.15 or later up to the fix versions, apply the relevant patch for your kernel branch.
Is CVE-2025-39858 actively exploited?

No — CVE-2025-39858 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.
What is NULL Pointer Dereference (CWE-476)?

The product dereferences a pointer that it expects to be valid but is NULL, typically causing a crash. View CWE-476 on MITRE CWE →