CVE-2022-48912 – This is a use-after-free vulnerability in the L... (How to Fix)

Q: What is the severity of CVE-2022-48912?

CVE-2022-48912 has a CVSS score of 7.8 (HIGH). This is a use-after-free vulnerability in the Linux kernel's netfilter subsystem that allows local attackers to potentially escalate privileges or cause denial of service. The vulnerability occurs when registering netfilter hooks, where freed memory can be accessed after mutex release. Systems running affected Linux kernel versions are vulnerable.

📋 TL;DR

This is a use-after-free vulnerability in the Linux kernel's netfilter subsystem that allows local attackers to potentially escalate privileges or cause denial of service. The vulnerability occurs when registering netfilter hooks, where freed memory can be accessed after mutex release. Systems running affected Linux kernel versions are vulnerable.

💻 Affected Systems

Products:

Linux Kernel

Versions: Kernel versions before the fix commits (specific versions vary by distribution, but generally 5.17-rc5 and earlier affected)

Operating Systems: Linux distributions using vulnerable kernel versions

Default Config Vulnerable: ⚠️ Yes

Notes: Requires netfilter subsystem to be enabled (common in most Linux distributions). The vulnerability is triggered when registering netfilter hooks.

📦 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

Local privilege escalation to root, kernel panic causing system crash, or arbitrary code execution in kernel context.

🟠

Likely Case

Kernel panic leading to denial of service or local privilege escalation if combined with other vulnerabilities.

🟢

If Mitigated

System crash requiring reboot, but no remote exploitation possible.

🌐 Internet-Facing: LOW - This is a local vulnerability requiring local access to the system.

🏢 Internal Only: MEDIUM - Internal users with shell access could exploit this for privilege escalation or DoS attacks.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ✅ No

Complexity: MEDIUM

Exploitation requires local access and knowledge of kernel memory layout. The vulnerability was discovered through syzkaller fuzzing.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Fixed in kernel commits: 05f7927b25d2635e87267ff6c79db79fb46cf313 and related commits

Vendor Advisory: https://git.kernel.org/stable/c/05f7927b25d2635e87267ff6c79db79fb46cf313

Restart Required: Yes

Instructions:

1. Update Linux kernel to version containing the fix commit. 2. For distributions: Use package manager to update kernel package. 3. Reboot system to load new kernel.

🔧 Temporary Workarounds

Disable netfilter modules

linux

Remove or blacklist netfilter modules to prevent hook registration

modprobe -r nf_synproxy_ipv6
echo 'blacklist nf_synproxy_ipv6' >> /etc/modprobe.d/blacklist.conf

🧯 If You Can't Patch

Restrict local user access to prevent exploitation
Implement strict SELinux/AppArmor policies to limit kernel access

🔍 How to Verify

Check if Vulnerable:

Check kernel version: uname -r and compare with distribution's patched version list

Check Version:

uname -r

Verify Fix Applied:

Verify kernel version after update and check that the fix commit is present in kernel source

📡 Detection & Monitoring

Log Indicators:

Kernel panic logs
KASAN reports of use-after-free in netfilter
System crashes during netfilter operations

Network Indicators:

None - this is a local vulnerability

SIEM Query:

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

📊 Metadata

CVE ID: CVE-2022-48912

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: August 22, 2024

Last Updated: August 27, 2024

🔗 References

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🔗 Related Vulnerabilities

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