CVE-2022-49014 – This is a use-after-free vulnerability in the L... (How to Fix)

Q: What is the severity of CVE-2022-49014?

CVE-2022-49014 has a CVSS score of 7.8 (HIGH). This is a use-after-free vulnerability in the Linux kernel's TUN/TAP network driver that occurs during device detachment. When exploited, it can cause kernel memory corruption leading to crashes, privilege escalation, or denial of service. Systems running vulnerable Linux kernel versions with TUN/TAP devices are affected.

📋 TL;DR

This is a use-after-free vulnerability in the Linux kernel's TUN/TAP network driver that occurs during device detachment. When exploited, it can cause kernel memory corruption leading to crashes, privilege escalation, or denial of service. Systems running vulnerable Linux kernel versions with TUN/TAP devices are affected.

💻 Affected Systems

Products:

Linux kernel

Versions: Kernel versions before the fix commits (specific versions vary by distribution, generally before kernel 6.1.0-rc5 with backports)

Operating Systems: Linux distributions using vulnerable kernel versions

Default Config Vulnerable: ✅ No

Notes: Requires TUN/TAP device usage and CAP_NET_ADMIN capability. Virtualization systems, VPN software, and container environments using TUN/TAP are particularly at risk.

📦 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 leading to system crash, potential privilege escalation to root, or remote code execution if combined with other vulnerabilities.

🟠

Likely Case

System instability, kernel crashes, or denial of service affecting network functionality.

🟢

If Mitigated

Limited impact if TUN/TAP devices are not in use or proper access controls prevent exploitation.

🌐 Internet-Facing: LOW - Requires local access or ability to create TUN/TAP devices, not directly exploitable over network.

🏢 Internal Only: MEDIUM - Local users or processes with CAP_NET_ADMIN can potentially exploit this vulnerability.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ✅ No

Complexity: MEDIUM

Exploitation requires local access and CAP_NET_ADMIN privileges. The vulnerability was discovered through syzkaller fuzzing.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Fixed in kernel commit 04b995e963229501401810dab89dc73e7f12d054 and backported to stable branches

Vendor Advisory: https://git.kernel.org/stable/c/04b995e963229501401810dab89dc73e7f12d054

Restart Required: Yes

Instructions:

1. Update Linux kernel to patched version from your distribution. 2. For RHEL/CentOS: yum update kernel. 3. For Ubuntu/Debian: apt update && apt upgrade linux-image-*. 4. Reboot system to load new kernel.

🔧 Temporary Workarounds

Restrict TUN/TAP device creation

linux

Limit which users can create TUN/TAP devices by removing CAP_NET_ADMIN from unnecessary users/processes

setcap -r CAP_NET_ADMIN /path/to/binary
capsh --drop=cap_net_admin -- -c "your_command"

Disable TUN/TAP module

linux

Prevent loading of TUN/TAP kernel module if not required

echo "install tun /bin/false" >> /etc/modprobe.d/disable-tun.conf
rmmod tun

🧯 If You Can't Patch

Implement strict access controls to prevent unauthorized users from creating TUN/TAP devices
Monitor for suspicious TUN/TAP device creation and kernel crash logs

🔍 How to Verify

Check if Vulnerable:

Check kernel version and if TUN/TAP module is loaded: lsmod | grep tun && uname -r

Check Version:

uname -r

Verify Fix Applied:

Verify kernel version is after fix commit: uname -r and check with distribution-specific advisory

📡 Detection & Monitoring

Log Indicators:

Kernel panic logs
KASAN reports of use-after-free in tun_detach()
System crashes during network device detachment

Network Indicators:

Unexpected TUN/TAP device creation
Network service disruptions

SIEM Query:

source="kernel" AND ("KASAN" OR "use-after-free" OR "tun_detach" OR "kernel panic")

📊 Metadata

CVE ID: CVE-2022-49014

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: October 21, 2024

Last Updated: October 24, 2024

🔗 References

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🔗 Related Vulnerabilities

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