What is CVE-2025-21886?

CVE-2025-21886 is a Medium severity Linux kernel vulnerability with a CVSS score of 5.5 out of 10, affecting Linux kernel versions from 6.12.13 onward and patched in 6.12.18 and 6.13.6. CVE-2025-21886 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

What is the CVSS score for CVE-2025-21886?

CVE-2025-21886 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-2025-21886?

Yes, CVE-2025-21886 has been patched. Fixed versions include 6.12.18 and 6.13.6. If you are running Linux kernel 6.12.13 or later up to the fix versions, apply the relevant patch for your kernel branch.

Is CVE-2025-21886 actively exploited?

CVE-2025-21886 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

CVE-2025-21886

Medium

In the Linux kernel, the following vulnerability has been resolved: RDMA/mlx5: Fix implicit ODP hang on parent deregistration Fix the destroy_unused_implicit_child_mr() to prevent hanging during parent deregistration as of below [1]. Upon entering destroy_unused_implicit_child_mr(), the reference count for the implicit MR parent is incremented using: refcount_inc_not_zero(). A corresponding decrement must be performed if free_implicit_child_mr_work() is not called. The code has been updated to properly manage the reference count that was incremented. [1] INFO: task python3:2157 blocked for more than 120 seconds. Not tainted 6.12.0-rc7+ #1633 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:python3 state:D stack:0 pid:2157 tgid:2157 ppid:1685 flags:0x00000000 Call Trace: <TASK> __schedule+0x420/0xd30 schedule+0x47/0x130 __mlx5_ib_dereg_mr+0x379/0x5d0 [mlx5_ib] ? __pfx_autoremove_wake_function+0x10/0x10 ib_dereg_mr_user+0x5f/0x120 [ib_core] ? lock_release+0xc6/0x280 destroy_hw_idr_uobject+0x1d/0x60 [ib_uverbs] uverbs_destroy_uobject+0x58/0x1d0 [ib_uverbs] uobj_destroy+0x3f/0x70 [ib_uverbs] ib_uverbs_cmd_verbs+0x3e4/0xbb0 [ib_uverbs] ? __pfx_uverbs_destroy_def_handler+0x10/0x10 [ib_uverbs] ? lock_acquire+0xc1/0x2f0 ? ib_uverbs_ioctl+0xcb/0x170 [ib_uverbs] ? ib_uverbs_ioctl+0x116/0x170 [ib_uverbs] ? lock_release+0xc6/0x280 ib_uverbs_ioctl+0xe7/0x170 [ib_uverbs] ? ib_uverbs_ioctl+0xcb/0x170 [ib_uverbs] __x64_sys_ioctl+0x1b0/0xa70 ? kmem_cache_free+0x221/0x400 do_syscall_64+0x6b/0x140 entry_SYSCALL_64_after_hwframe+0x76/0x7e RIP: 0033:0x7f20f21f017b RSP: 002b:00007ffcfc4a77c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007ffcfc4a78d8 RCX: 00007f20f21f017b RDX: 00007ffcfc4a78c0 RSI: 00000000c0181b01 RDI: 0000000000000003 RBP: 00007ffcfc4a78a0 R08: 000056147d125190 R09: 00007f20f1f14c60 R10: 0000000000000001 R11: 0000000000000246 R12: 00007ffcfc4a7890 R13: 000000000000001c R14: 000056147d100fc0 R15: 00007f20e365c9d0 </TASK>

Package Linux Kernel

Published 2025-03-27

Last modified 2025-10-29

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 6.12.13, 6.13.2 and later are affected. Fixed in 6.12.18, 6.13.6 and their respective stable series.

Affected from

≥ 6.12.13 ≥ 6.13.2

Fixed in

✓ 6.12.18 6.12.x ✓ 6.13.6 6.13.x

References

3 total

Kernel Git
https://git.kernel.org/stable/c/3d8c6f26893d55fab218ad086719de1fc9bb86ba

Patch
Kernel Git
https://git.kernel.org/stable/c/a095ede2daca49d15e74d66d014883f2fa8bb924

Patch
Kernel Git
https://git.kernel.org/stable/c/cb96ae783e7249e8e5a50c22952c0bb2983133df

Patch

Details

CVE ID CVE-2025-21886

Severity Medium

CVSS score 5.5 / 10

CVSS version 3.1

Published 2025-03-27

Modified 2025-10-29

KEV No

Patch

Yes

Package linux

Frequently asked questions

What is CVE-2025-21886?

CVE-2025-21886 is a Medium severity Linux kernel vulnerability with a CVSS score of 5.5 out of 10 . It affects Linux kernel versions from 6.12.13 onward and has been patched in 6.12.18 and 6.13.6. CVE-2025-21886 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.
What is the CVSS score for CVE-2025-21886?

CVE-2025-21886 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-2025-21886?

Yes. CVE-2025-21886 has been patched. Fixed versions include 6.12.18 and 6.13.6. If you are running Linux kernel 6.12.13 or later up to the fix versions, apply the relevant patch for your kernel branch.
Is CVE-2025-21886 actively exploited?

No. CVE-2025-21886 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.