CVE-2025-38621

Medium

In the Linux kernel, the following vulnerability has been resolved: md: make rdev_addable usable for rcu mode Our testcase trigger panic: BUG: kernel NULL pointer dereference, address: 00000000000000e0 ... Oops: Oops: 0000 [#1] SMP NOPTI CPU: 2 UID: 0 PID: 85 Comm: kworker/2:1 Not tainted 6.16.0+ #94 PREEMPT(none) Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.1-2.fc37 04/01/2014 Workqueue: md_misc md_start_sync RIP: 0010:rdev_addable+0x4d/0xf0 ... Call Trace: <TASK> md_start_sync+0x329/0x480 process_one_work+0x226/0x6d0 worker_thread+0x19e/0x340 kthread+0x10f/0x250 ret_from_fork+0x14d/0x180 ret_from_fork_asm+0x1a/0x30 </TASK> Modules linked in: raid10 CR2: 00000000000000e0 ---[ end trace 0000000000000000 ]--- RIP: 0010:rdev_addable+0x4d/0xf0 md_spares_need_change in md_start_sync will call rdev_addable which protected by rcu_read_lock/rcu_read_unlock. This rcu context will help protect rdev won't be released, but rdev->mddev will be set to NULL before we call synchronize_rcu in md_kick_rdev_from_array. Fix this by using READ_ONCE and check does rdev->mddev still alive.

Package Linux Kernel
Published 2025-08-22
Last modified 2025-11-26
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-2025-38621 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 6.7 and later are affected. Fixed in 6.16.1, 6.17 and their respective stable series.

Affected from
≥ 6.7
Fixed in
✓ 6.16.1 6.16.x ✓ 6.17

References

The following references provide additional information about CVE-2025-38621 including vendor advisories, patch commits, exploit details, and third-party analysis. Links are sourced from the NIST NVD database.

Frequently asked questions

  • What is CVE-2025-38621?

    CVE-2025-38621 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 6.7 onward and has been patched in 6.16.1 and 6.17. CVE-2025-38621 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

  • What is the CVSS score for CVE-2025-38621?

    CVE-2025-38621 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-2025-38621?

    Yes — CVE-2025-38621 has been patched. Fixed versions include 6.16.1 and 6.17. If you are running Linux kernel 6.7 or later up to the fix versions, apply the relevant patch for your kernel branch.

  • Is CVE-2025-38621 actively exploited?

    No — CVE-2025-38621 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 →

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