CVE-2024-27020 – This CVE describes a race condition vulnerabili... (How to Fix)

Q: What is the severity of CVE-2024-27020?

CVE-2024-27020 has a CVSS score of 7.0 (HIGH). This CVE describes a race condition vulnerability in the Linux kernel's netfilter nf_tables subsystem. It allows concurrent access to the nf_tables_expressions list without proper synchronization, potentially leading to memory corruption or system crashes. All Linux systems using affected kernel versions with nf_tables enabled are vulnerable.

📋 TL;DR

This CVE describes a race condition vulnerability in the Linux kernel's netfilter nf_tables subsystem. It allows concurrent access to the nf_tables_expressions list without proper synchronization, potentially leading to memory corruption or system crashes. All Linux systems using affected kernel versions with nf_tables enabled are vulnerable.

💻 Affected Systems

Products:

Linux kernel

Versions: Specific affected versions not explicitly stated in CVE, but patches are available in stable kernel trees. Likely affects multiple recent versions before fixes.

Operating Systems: Linux distributions using vulnerable kernel versions

Default Config Vulnerable: ✅ No

Notes: Only vulnerable if nf_tables subsystem is enabled and in use. Many distributions enable nf_tables by default for firewall functionality.

📦 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 →

⚠️ Risk & Real-World Impact

🔴

Worst Case

Kernel panic or system crash leading to denial of service, or potential privilege escalation if memory corruption can be exploited to execute arbitrary code.

🟠

Likely Case

System instability, kernel crashes, or denial of service due to race condition triggering during concurrent nf_tables operations.

🟢

If Mitigated

Minimal impact if proper kernel hardening and isolation are in place, though race conditions remain unpredictable.

🌐 Internet-Facing: MEDIUM - Systems with nf_tables firewall rules exposed to network traffic could trigger the race condition through packet processing.

🏢 Internal Only: LOW - Requires local access or specific nf_tables operations to trigger, though containerized environments could increase risk.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ✅ No

Complexity: HIGH

Race condition exploitation requires precise timing and specific conditions. No public exploits known at this time.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Patches available in stable kernel trees (commits provided in references)

Vendor Advisory: https://git.kernel.org/stable/c/01f1a678b05ade4b1248019c2dcca773aebbeb7f

Restart Required: Yes

Instructions:

1. Update to a patched kernel version from your distribution's repositories. 2. Reboot the system to load the new kernel. 3. Verify the fix by checking kernel version or testing nf_tables functionality.

🔧 Temporary Workarounds

Disable nf_tables

linux

Temporarily disable the nf_tables subsystem if not required

modprobe -r nf_tables
echo 'blacklist nf_tables' > /etc/modprobe.d/disable-nftables.conf

Use legacy iptables

linux

Switch to legacy iptables firewall instead of nf_tables

systemctl stop nftables
systemctl disable nftables
apt-get install iptables
yum install iptables-services

🧯 If You Can't Patch

Isolate affected systems from untrusted networks
Implement strict access controls to limit who can modify nf_tables rules

🔍 How to Verify

Check if Vulnerable:

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

Check Version:

uname -r

Verify Fix Applied:

Verify kernel version is patched by checking commit history or comparing against fixed versions in references

📡 Detection & Monitoring

Log Indicators:

Kernel panic messages in /var/log/kern.log or dmesg
nf_tables related crash reports
System instability or unexpected reboots

Network Indicators:

Unexpected firewall rule changes
Network connectivity issues when nf_tables is active

SIEM Query:

source="kernel" AND ("panic" OR "Oops" OR "BUG") AND "nf_tables"

📊 Metadata

CVE ID: CVE-2024-27020

CVSS v3 Score: 7.0 (HIGH)

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

CWE: CWE-362

Published: May 1, 2024

Last Updated: November 4, 2025

🔗 References

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🔗 Related Vulnerabilities

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