CVE-2021-47352 – This CVE addresses a vulnerability in the Linux... (How to Fix)

Q: What is the severity of CVE-2021-47352?

CVE-2021-47352 has a CVSS score of 7.8 (HIGH). This CVE addresses a vulnerability in the Linux kernel's virtio-net driver where insufficient validation of 'used length' values from untrusted virtual devices could lead to data corruption or loss. Systems using virtualization with virtio-net devices are affected, particularly cloud environments and virtualized infrastructure. The vulnerability allows a malicious or compromised virtual device to corrupt kernel memory.

📋 TL;DR

This CVE addresses a vulnerability in the Linux kernel's virtio-net driver where insufficient validation of 'used length' values from untrusted virtual devices could lead to data corruption or loss. Systems using virtualization with virtio-net devices are affected, particularly cloud environments and virtualized infrastructure. The vulnerability allows a malicious or compromised virtual device to corrupt kernel memory.

💻 Affected Systems

Products:

Linux kernel

Versions: Specific affected versions not explicitly stated in CVE, but patches exist for multiple stable branches (see references).

Operating Systems: Linux distributions using affected kernel versions

Default Config Vulnerable: ⚠️ Yes

Notes: Requires virtio-net driver usage in virtualization environments (KVM, QEMU, etc.). Physical systems without virtualization are not affected.

📦 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 memory corruption leading to system crash, denial of service, or potential privilege escalation if combined with other vulnerabilities.

🟠

Likely Case

Data corruption or loss in network operations, system instability, or denial of service affecting virtual machine performance.

🟢

If Mitigated

Minimal impact with proper input validation preventing malicious length values from being processed.

🌐 Internet-Facing: LOW - Requires access to virtual device interface, not directly internet-exposed.

🏢 Internal Only: MEDIUM - Exploitable by malicious or compromised virtual devices within the same host, affecting cloud and virtualization environments.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ✅ No

Complexity: MEDIUM

Exploitation requires control over a virtual device or ability to send malicious virtio-net packets. No public exploits known at CVE publication.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Multiple stable kernel versions with commits: 3133e01514c3c498f2b01ff210ee6134b70c663c, ad993a95c508417acdeb15244109e009e50d8758, ba710baa1cc1b17a0483f7befe03e696efd17292, c1b40d1959517ff2ea473d40eeab4691d6d62462, c92298d228f61589dd21657af2bea95fc866b813

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

Restart Required: Yes

Instructions:

1. Update Linux kernel to patched version from your distribution. 2. For custom kernels, apply relevant commits from kernel.org. 3. Reboot system to load new kernel.

🔧 Temporary Workarounds

Disable virtio-net

linux

Replace virtio-net with alternative virtual network drivers if possible (not recommended for production).

Modify VM configuration to use e1000 or other emulated NIC instead of virtio

🧯 If You Can't Patch

Isolate untrusted virtual machines to separate physical hosts
Implement strict access controls for virtual device management interfaces

🔍 How to Verify

Check if Vulnerable:

Check kernel version and compare with patched versions from kernel.org. Examine if virtio-net is in use: 'lsmod | grep virtio_net'

Check Version:

uname -r

Verify Fix Applied:

Verify kernel version includes one of the fix commits: 'uname -r' and check kernel source or distribution patch notes.

📡 Detection & Monitoring

Log Indicators:

Kernel oops or panic messages related to virtio_net, network corruption errors

Network Indicators:

Unusual virtio-net packet patterns from virtual devices

SIEM Query:

kernel: "virtio_net" AND ("panic" OR "oops" OR "corruption")

📊 Metadata

CVE ID: CVE-2021-47352

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-787

Published: May 21, 2024

Last Updated: November 14, 2025

🔗 References

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🔗 Related Vulnerabilities

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