CVE-2025-22126 – This CVE describes a use-after-free (UAF) vulne... (How to Fix)

Q: What is the severity of CVE-2025-22126?

CVE-2025-22126 has a CVSS score of 7.8 (HIGH). This CVE describes a use-after-free (UAF) vulnerability in the Linux kernel's MD (Multiple Device) subsystem. The race condition occurs when iterating through the all_mddevs list during system reboot or shutdown, potentially allowing an attacker to execute arbitrary code with kernel privileges. All Linux systems using MD RAID or software RAID functionality are affected.

📋 TL;DR

This CVE describes a use-after-free (UAF) vulnerability in the Linux kernel's MD (Multiple Device) subsystem. The race condition occurs when iterating through the all_mddevs list during system reboot or shutdown, potentially allowing an attacker to execute arbitrary code with kernel privileges. All Linux systems using MD RAID or software RAID functionality are affected.

💻 Affected Systems

Products:

Linux kernel

Versions: Specific affected versions not specified in CVE description, but patches exist for stable kernel trees.

Operating Systems: Linux distributions using vulnerable kernel versions

Default Config Vulnerable: ⚠️ Yes

Notes: Only affects systems using MD (software RAID) functionality. Systems without MD configured are not vulnerable.

📦 What is this software?

Linux Kernel by Linux

The Linux Kernel is the core component of the Linux operating system, serving as the critical interface between computer hardware and software processes. As the heart of millions of servers, cloud infrastructure, embedded systems, Android devices, and IoT deployments worldwide, the Linux Kernel mana...

Learn more about Linux Kernel →

Linux Kernel by Linux

The Linux Kernel is the core component of the Linux operating system, serving as the critical interface between computer hardware and software processes. As the heart of millions of servers, cloud infrastructure, embedded systems, Android devices, and IoT deployments worldwide, the Linux Kernel mana...

Learn more about Linux Kernel →

Linux Kernel by Linux

The Linux Kernel is the core component of the Linux operating system, serving as the critical interface between computer hardware and software processes. As the heart of millions of servers, cloud infrastructure, embedded systems, Android devices, and IoT deployments worldwide, the Linux Kernel mana...

Learn more about Linux Kernel →

Linux Kernel by Linux

The Linux Kernel is the core component of the Linux operating system, serving as the critical interface between computer hardware and software processes. As the heart of millions of servers, cloud infrastructure, embedded systems, Android devices, and IoT deployments worldwide, the Linux Kernel mana...

Learn more about Linux Kernel →

⚠️ Risk & Real-World Impact

🔴

Worst Case

Kernel privilege escalation leading to full system compromise, data corruption, or denial of service through kernel panic.

🟠

Likely Case

System crash or instability during reboot/shutdown operations, potentially requiring physical intervention to recover.

🟢

If Mitigated

Minimal impact if systems are patched before exploitation attempts occur.

🌐 Internet-Facing: LOW - Requires local access or ability to trigger MD operations.

🏢 Internal Only: MEDIUM - Local attackers or malicious processes could exploit this to gain kernel privileges.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ✅ No

Complexity: HIGH - Requires precise timing and ability to manipulate MD devices.

Exploitation requires local access and ability to trigger MD operations during system reboot/shutdown.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Patched in stable kernel commits: 5462544ccbad3fc938a71b01fa5bd3a0dc2b750a, 8542870237c3a48ff049b6c5df5f50c8728284fa, ca9f84de76723b358dfc0606668efdca54afc2e5, d69a23d8e925f8052d657652a6875ec2712c7e33, e2a9f73ee408a460f4c9dfe03b4741d6b11652b8

Vendor Advisory: https://git.kernel.org/stable/c/5462544ccbad3fc938a71b01fa5bd3a0dc2b750a

Restart Required: Yes

Instructions:

1. Update Linux kernel to version containing the fix. 2. Check with your distribution for specific kernel updates. 3. Reboot system after kernel update.

🔧 Temporary Workarounds

Disable MD subsystem

linux

Remove or disable MD (software RAID) functionality if not needed.

modprobe -r md_mod
echo 'blacklist md_mod' > /etc/modprobe.d/disable-md.conf

🧯 If You Can't Patch

Restrict local user access to systems using MD functionality
Monitor for unusual MD operations or system crashes during reboot

🔍 How to Verify

Check if Vulnerable:

Check kernel version and if MD module is loaded: lsmod | grep md_mod && uname -r

Check Version:

uname -r

Verify Fix Applied:

Verify kernel version is updated to include the fix commits and test system stability during reboot with MD operations.

📡 Detection & Monitoring

Log Indicators:

Kernel panic messages related to MD subsystem
System crashes during reboot/shutdown
UAF-related kernel oops messages

Network Indicators:

None - local vulnerability only

SIEM Query:

search 'kernel: BUG: unable to handle kernel' OR 'kernel: general protection fault' AND 'md'

📊 Metadata

CVE ID: CVE-2025-22126

CVSS v3 Score: 7.8 (HIGH)

CVSS Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CWE: CWE-416

EPSS Score: 0.06% exploit probability (19.6th percentile)

Published: April 16, 2025

Last Updated: November 3, 2025

🔗 References

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