CVE-2025-21905 – This CVE describes an out-of-bounds read vulner... (How to Fix)

Q: What is the severity of CVE-2025-21905?

CVE-2025-21905 has a CVSS score of 7.1 (HIGH). This CVE describes an out-of-bounds read vulnerability in the iwlwifi driver in the Linux kernel. When reading firmware files without proper null termination, the driver could read beyond buffer boundaries, potentially accessing unauthorized memory. This affects Linux systems using Intel wireless hardware with the iwlwifi driver.

📋 TL;DR

This CVE describes an out-of-bounds read vulnerability in the iwlwifi driver in the Linux kernel. When reading firmware files without proper null termination, the driver could read beyond buffer boundaries, potentially accessing unauthorized memory. This affects Linux systems using Intel wireless hardware with the iwlwifi driver.

💻 Affected Systems

Products:

Linux kernel iwlwifi driver

Versions: Linux kernel versions before the fix commits (specific versions vary by distribution)

Operating Systems: Linux distributions using affected kernel versions

Default Config Vulnerable: ⚠️ Yes

Notes: Requires Intel wireless hardware using iwlwifi driver. Vulnerability triggered when loading firmware files.

📦 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...

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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 →

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, system crash, or potential information disclosure if the out-of-bounds read accesses sensitive kernel memory regions.

🟠

Likely Case

System instability, kernel crashes, or denial of service when processing malformed firmware files.

🟢

If Mitigated

Limited impact with proper access controls preventing malicious firmware loading.

🌐 Internet-Facing: LOW - Requires local access or ability to load firmware files.

🏢 Internal Only: MEDIUM - Could be exploited by local users or through malicious firmware updates.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ✅ No

Complexity: MEDIUM

Exploitation requires ability to load malicious firmware files, typically requiring local access or compromised update mechanisms.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Kernel versions containing commits: 38f0d398b6d7640d223db69df022c4a232f24774, 47616b82f2d42ea2060334746fed9a2988d845c9, 59cdda202829d1d6a095d233386870a59aff986f, 88ed69f924638c7503644e1f8eed1e976f3ffa7a, b02f8d5a71c8571ccf77f285737c566db73ef5e5

Vendor Advisory: https://git.kernel.org/stable/c/38f0d398b6d7640d223db69df022c4a232f24774

Restart Required: Yes

Instructions:

1. Update Linux kernel to patched version from your distribution. 2. Reboot system to load new kernel. 3. Verify iwlwifi module loads correctly.

🔧 Temporary Workarounds

Disable iwlwifi module

linux

Temporarily disable the vulnerable driver if wireless not required

sudo modprobe -r iwlwifi
echo 'blacklist iwlwifi' | sudo tee /etc/modprobe.d/blacklist-iwlwifi.conf

🧯 If You Can't Patch

Restrict firmware loading to trusted sources only
Implement strict file integrity monitoring for firmware files

🔍 How to Verify

Check if Vulnerable:

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

Check Version:

uname -r

Verify Fix Applied:

Verify kernel version is after fix commits and iwlwifi module loads without errors in dmesg

📡 Detection & Monitoring

Log Indicators:

Kernel panic messages
iwlwifi driver crash logs in dmesg
Out-of-bounds memory access warnings

Network Indicators:

Unexpected wireless interface disconnections
Failed firmware loading attempts

SIEM Query:

source="kernel" AND ("iwlwifi" OR "firmware") AND ("panic" OR "oops" OR "segfault")

📊 Metadata

CVE ID: CVE-2025-21905

CVSS v3 Score: 7.1 (HIGH)

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

CWE: CWE-125

EPSS Score: 0.07% exploit probability (22.3th percentile)

Published: April 1, 2025

Last Updated: November 3, 2025

🔗 References

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