CVE-2023-6817 – This CVE describes a use-after-free vulnerabili... (How to Fix)

Q: What is the severity of CVE-2023-6817?

CVE-2023-6817 has a CVSS score of 7.8 (HIGH). This CVE describes a use-after-free vulnerability in the Linux kernel's netfilter nf_tables component. It allows local attackers to escalate privileges from an unprivileged user to root. All Linux systems using affected kernel versions with nf_tables enabled are vulnerable.

📋 TL;DR

This CVE describes a use-after-free vulnerability in the Linux kernel's netfilter nf_tables component. It allows local attackers to escalate privileges from an unprivileged user to root. All Linux systems using affected kernel versions with nf_tables enabled are vulnerable.

💻 Affected Systems

Products:

Linux kernel

Versions: Kernel versions before commit 317eb9685095678f2c9f5a8189de698c5354316a

Operating Systems: Linux distributions using affected kernel versions

Default Config Vulnerable: ⚠️ Yes

Notes: Requires nf_tables subsystem to be enabled/loaded. Most modern Linux distributions have this enabled by default.

📦 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 →

⚠️ Risk & Real-World Impact

🔴

Worst Case

Full root privilege escalation leading to complete system compromise, data theft, persistence installation, and lateral movement.

🟠

Likely Case

Local privilege escalation allowing attackers to gain root access on compromised systems.

🟢

If Mitigated

Limited impact if proper access controls restrict local user accounts and kernel hardening measures are in place.

🌐 Internet-Facing: LOW - This is a local privilege escalation vulnerability requiring local access.

🏢 Internal Only: HIGH - Any compromised user account on affected systems can escalate to root.

🎯 Exploit Status

Public PoC: ⚠️ Yes

Weaponized: LIKELY

Unauthenticated Exploit: ✅ No

Complexity: MEDIUM

Exploit requires local access and knowledge of kernel exploitation techniques. Public exploit code exists in security advisories.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Kernel with commit 317eb9685095678f2c9f5a8189de698c5354316a or later

Vendor Advisory: http://packetstormsecurity.com/files/177029/Kernel-Live-Patch-Security-Notice-LSN-0100-1.html

Restart Required: Yes

Instructions:

1. Update kernel package from your distribution's repositories. 2. Reboot the system. 3. Verify the fix is applied by checking kernel version or commit hash.

🔧 Temporary Workarounds

Disable nf_tables module

linux

Unload the nf_tables kernel module to prevent exploitation

sudo rmmod nf_tables
sudo modprobe -r nf_tables

Blacklist nf_tables module

linux

Prevent nf_tables from loading at boot

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

🧯 If You Can't Patch

Restrict local user access and implement strict privilege separation
Implement kernel hardening measures like SELinux/AppArmor with strict policies

🔍 How to Verify

Check if Vulnerable:

Check if nf_tables module is loaded: lsmod | grep nf_tables. If loaded and kernel version is before the fix commit, system is vulnerable.

Check Version:

uname -r

Verify Fix Applied:

Check kernel version includes commit 317eb9685095678f2c9f5a8189de698c5354316a or verify with: sudo cat /proc/version

📡 Detection & Monitoring

Log Indicators:

Kernel oops messages
System crash logs
Unusual privilege escalation attempts

Network Indicators:

None - this is a local exploit

SIEM Query:

Search for kernel panic logs, privilege escalation events, or failed sudo/root access attempts from unusual users

📊 Metadata

CVE ID: CVE-2023-6817

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-416

Published: December 18, 2023

Last Updated: February 13, 2025

🔗 References

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🔗 Related Vulnerabilities

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