CVE-2021-47137 – A memory corruption vulnerability in the Linux ... (How to Fix)

Q: What is the severity of CVE-2021-47137?

CVE-2021-47137 has a CVSS score of 7.8 (HIGH). A memory corruption vulnerability in the Linux kernel's Lantiq network driver allows attackers to corrupt kernel memory when memory allocation or DMA mapping fails during packet reception. This affects systems using Lantiq network hardware with vulnerable kernel versions. Successful exploitation could lead to system crashes or arbitrary code execution.

📋 TL;DR

A memory corruption vulnerability in the Linux kernel's Lantiq network driver allows attackers to corrupt kernel memory when memory allocation or DMA mapping fails during packet reception. This affects systems using Lantiq network hardware with vulnerable kernel versions. Successful exploitation could lead to system crashes or arbitrary code execution.

💻 Affected Systems

Products:

Linux kernel with Lantiq network driver

Versions: Kernel versions before fixes in stable trees (specific commits listed in references)

Operating Systems: Linux distributions using affected kernel versions

Default Config Vulnerable: ⚠️ Yes

Notes: Only affects systems with Lantiq network hardware/SoCs (commonly used in routers, networking equipment).

📦 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 →

⚠️ Risk & Real-World Impact

🔴

Worst Case

Kernel memory corruption leading to arbitrary code execution with kernel privileges, potentially resulting in complete system compromise.

🟠

Likely Case

System instability, kernel panics, or denial of service due to memory corruption.

🟢

If Mitigated

System remains stable with proper patching; failed memory allocations result in dropped packets without corruption.

🌐 Internet-Facing: MEDIUM - Requires network access to vulnerable interface but exploitation depends on triggering memory allocation failures.

🏢 Internal Only: MEDIUM - Same exploitation requirements as internet-facing, but internal network access needed.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ⚠️ Yes

Complexity: MEDIUM

Exploitation requires network access to trigger memory allocation failures in RX ring processing.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Kernel versions containing commits: 46dd4abced3cb2c912916f4a5353e0927db0c4a2, 5ac72351655f8b033a2935646f53b7465c903418, 8bb1077448d43a871ed667520763e3b9f9b7975d, c7718ee96dbc2f9c5fc3b578abdf296dd44b9c20

Vendor Advisory: https://git.kernel.org/stable/c/46dd4abced3cb2c912916f4a5353e0927db0c4a2

Restart Required: Yes

Instructions:

1. Update Linux kernel to patched version from distribution vendor. 2. Reboot system to load new kernel. 3. Verify kernel version after reboot.

🔧 Temporary Workarounds

Disable Lantiq network interface

linux

Temporarily disable the vulnerable network interface if not required

ip link set <interface_name> down

🧯 If You Can't Patch

Isolate affected systems from untrusted networks
Implement strict network segmentation and firewall rules

🔍 How to Verify

Check if Vulnerable:

Check kernel version and if Lantiq driver is loaded: 'uname -r' and 'lsmod | grep lantiq'

Check Version:

uname -r

Verify Fix Applied:

Verify kernel version is updated and contains the fix commits: 'uname -r' and check kernel changelog

📡 Detection & Monitoring

Log Indicators:

Kernel panic logs
Memory corruption errors in dmesg
Network interface errors

Network Indicators:

Unusual packet patterns targeting Lantiq interfaces
Increased packet drops

SIEM Query:

source="kernel" AND ("panic" OR "corruption" OR "lantiq")

📊 Metadata

CVE ID: CVE-2021-47137

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-770

Published: March 25, 2024

Last Updated: March 19, 2025

🔗 References

📤 Share & Export

📄 Export Markdown 📋 Export JSON

🔗 Related Vulnerabilities

If you're affected by CVE-2021-47137, you might also want to check these: