CVE-2023-52840 – This CVE describes a use-after-free vulnerabili... (How to Fix)

Q: What is the severity of CVE-2023-52840?

CVE-2023-52840 has a CVSS score of 7.8 (HIGH). This CVE describes a use-after-free vulnerability in the Linux kernel's synaptics-rmi4 touchpad driver. When exploited, it could allow local attackers to crash the system or potentially execute arbitrary code with kernel privileges. This affects Linux systems using the vulnerable driver.

📋 TL;DR

This CVE describes a use-after-free vulnerability in the Linux kernel's synaptics-rmi4 touchpad driver. When exploited, it could allow local attackers to crash the system or potentially execute arbitrary code with kernel privileges. This affects Linux systems using the vulnerable driver.

💻 Affected Systems

Products:

Linux kernel with synaptics-rmi4 driver

Versions: Linux kernel versions before the fix commits (specific versions vary by distribution)

Operating Systems: Linux distributions using affected kernel versions

Default Config Vulnerable: ⚠️ Yes

Notes: Only affects systems with synaptics touchpad hardware using the rmi4 driver. Many laptops and some desktops may be vulnerable if using this driver.

📦 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 →

⚠️ Risk & Real-World Impact

🔴

Worst Case

Local privilege escalation to kernel-level access, potentially leading to full system compromise, data theft, or persistent backdoor installation.

🟠

Likely Case

Kernel panic or system crash causing denial of service, requiring reboot to restore functionality.

🟢

If Mitigated

Limited to denial of service if kernel hardening features like KASLR and SMAP/SMEP are enabled and effective.

🌐 Internet-Facing: LOW - Requires local access to the system; not directly exploitable over network.

🏢 Internal Only: MEDIUM - Local attackers or malicious users could exploit this to gain elevated privileges or crash systems.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ✅ No

Complexity: MEDIUM

Requires local access and knowledge of kernel exploitation techniques. No public exploits known at this time.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Fixed in kernel commits: 2f236d8638f5b43e0c72919a6a27fe286c32053f, 303766bb92c5c225cf40f9bbbe7e29749406e2f2, 50d12253666195a14c6cd2b81c376e2dbeedbdff, 6c71e065befb2fae8f1461559b940c04e1071bd5, 7082b1fb5321037bc11ba1cf2d7ed23c6b2b521f

Vendor Advisory: https://git.kernel.org/stable/c/2f236d8638f5b43e0c72919a6a27fe286c32053f

Restart Required: Yes

Instructions:

1. Update Linux kernel to version containing the fix commits. 2. Check your distribution's security advisories for specific patched versions. 3. Reboot system after kernel update.

🔧 Temporary Workarounds

Disable synaptics-rmi4 driver

linux

Blacklist or disable the vulnerable driver if touchpad functionality is not required

echo 'blacklist rmi4' >> /etc/modprobe.d/blacklist.conf
update-initramfs -u
reboot

🧯 If You Can't Patch

Restrict local user access to systems with vulnerable driver
Implement strict privilege separation and limit sudo/root access

🔍 How to Verify

Check if Vulnerable:

Check kernel version and if synaptics-rmi4 module is loaded: lsmod | grep rmi4

Check Version:

uname -r

Verify Fix Applied:

Verify kernel version is updated beyond fix commits and rmi4 module version matches patched version

📡 Detection & Monitoring

Log Indicators:

Kernel oops messages in /var/log/kern.log or dmesg
System crashes or unexpected reboots

Network Indicators:

No network indicators - local exploit only

SIEM Query:

Search for kernel panic events or module loading failures related to rmi4 driver

📊 Metadata

CVE ID: CVE-2023-52840

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: May 21, 2024

Last Updated: December 31, 2024

🔗 References

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🔗 Related Vulnerabilities

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