CVE-2025-21668 – A missing loop break condition in the imx8mp-bl... (How to Fix)

Q: What is the severity of CVE-2025-21668?

CVE-2025-21668 has a CVSS score of 5.5 (MEDIUM). A missing loop break condition in the imx8mp-blk-ctrl power domain driver in the Linux kernel causes an out-of-bounds access during device shutdown, leading to a kernel panic. This affects systems using the i.MX8MP processor with the vulnerable driver. The vulnerability can cause system crashes during shutdown or reboot operations.

📋 TL;DR

A missing loop break condition in the imx8mp-blk-ctrl power domain driver in the Linux kernel causes an out-of-bounds access during device shutdown, leading to a kernel panic. This affects systems using the i.MX8MP processor with the vulnerable driver. The vulnerability can cause system crashes during shutdown or reboot operations.

💻 Affected Systems

Products:

Linux kernel with imx8mp-blk-ctrl driver

Versions: Linux kernel versions containing the vulnerable imx8mp-blk-ctrl driver code prior to fixes in stable releases

Operating Systems: Linux distributions using affected kernel versions

Default Config Vulnerable: ⚠️ Yes

Notes: Only affects systems with i.MX8MP processors where the imx8mp-blk-ctrl driver is loaded and used.

📦 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 →

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 →

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 panic leading to system crash and denial of service during shutdown/reboot operations, potentially causing data loss or corruption.

🟠

Likely Case

System crash during shutdown/reboot operations, requiring manual intervention to restore service.

🟢

If Mitigated

No impact if patched or if the vulnerable driver is not loaded.

🌐 Internet-Facing: LOW - This is a local kernel driver issue not directly exploitable over network.

🏢 Internal Only: MEDIUM - Local users or processes triggering shutdown/reboot can cause system crashes.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: NO

Unauthenticated Exploit: ✅ No

Complexity: LOW - Triggering requires ability to initiate system shutdown/reboot.

Exploitation requires local access to trigger shutdown/reboot operations. No remote exploitation vector exists.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Patches available in stable kernel releases via provided git commits

Vendor Advisory: https://lists.debian.org/debian-lts-announce/2025/03/msg00001.html

Restart Required: Yes

Instructions:

1. Update Linux kernel to version containing fixes from provided git commits. 2. For Debian systems, apply security updates via apt. 3. Reboot system to load patched kernel.

🔧 Temporary Workarounds

Disable imx8mp-blk-ctrl driver

linux

Prevent loading of the vulnerable driver module

echo 'blacklist imx8mp-blk-ctrl' >> /etc/modprobe.d/blacklist.conf
rmmod imx8mp_blk_ctrl

🧯 If You Can't Patch

Restrict local user access to prevent unauthorized shutdown/reboot commands
Implement monitoring for system crashes and kernel panics related to shutdown operations

🔍 How to Verify

Check if Vulnerable:

Check if imx8mp-blk-ctrl driver is loaded: lsmod | grep imx8mp_blk_ctrl

Check Version:

uname -r

Verify Fix Applied:

Check kernel version against patched releases and verify driver loads without issues during shutdown tests

📡 Detection & Monitoring

Log Indicators:

Kernel panic messages during shutdown
Out-of-bounds access errors in kernel logs
System crash reports during reboot operations

Network Indicators:

None - local vulnerability only

SIEM Query:

source="kernel" AND ("panic" OR "oops" OR "out-of-bounds") AND ("shutdown" OR "reboot")

📊 Metadata

CVE ID: CVE-2025-21668

CVSS v3 Score: 5.5 (MEDIUM)

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

CWE: CWE-835

Published: January 31, 2025

Last Updated: November 3, 2025

🔗 References

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🔗 Related Vulnerabilities

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