CVE-2023-52806 – A null pointer dereference vulnerability in the... (How to Fix)

Q: What is the severity of CVE-2023-52806?

CVE-2023-52806 has a CVSS score of 5.5 (MEDIUM). A null pointer dereference vulnerability in the Linux kernel's ALSA HDA subsystem allows local attackers to crash the system or potentially escalate privileges. This affects Linux systems with ALSA audio drivers when users attempt to assign COUPLED streams during code-loading scenarios. The vulnerability requires local access to the system.

📋 TL;DR

A null pointer dereference vulnerability in the Linux kernel's ALSA HDA subsystem allows local attackers to crash the system or potentially escalate privileges. This affects Linux systems with ALSA audio drivers when users attempt to assign COUPLED streams during code-loading scenarios. The vulnerability requires local access to the system.

💻 Affected Systems

Products:

Linux kernel

Versions: Specific affected kernel versions not specified in CVE, but patches exist for stable branches

Operating Systems: Linux distributions using affected kernel versions

Default Config Vulnerable: ⚠️ Yes

Notes: Requires ALSA HDA audio subsystem and users attempting to assign COUPLED streams during code-loading operations.

📦 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

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

🟠

Likely Case

System crash or kernel panic when attempting to assign COUPLED streams during audio code-loading operations.

🟢

If Mitigated

No impact if proper access controls prevent local users from executing privileged audio operations.

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

🏢 Internal Only: MEDIUM - Local users or processes could trigger the vulnerability, potentially causing system instability.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ✅ No

Complexity: MEDIUM

Requires local access and specific conditions to trigger the null pointer dereference.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Patches available in stable kernel branches via provided git commits

Vendor Advisory: https://git.kernel.org/stable/c/2527775616f3638f4fd54649eba8c7b84d5e4250

Restart Required: Yes

Instructions:

1. Update Linux kernel to patched version. 2. Check distribution-specific security advisories. 3. Reboot system after kernel update.

🔧 Temporary Workarounds

Restrict audio device access

linux

Limit access to audio devices to prevent unauthorized users from triggering the vulnerability

chmod 600 /dev/snd/*
setfacl -m u:audio:rw /dev/snd/*

🧯 If You Can't Patch

Implement strict access controls to prevent unauthorized users from accessing audio subsystems
Monitor system logs for kernel panic events related to ALSA HDA operations

🔍 How to Verify

Check if Vulnerable:

Check kernel version and compare with patched versions in git commits. Use: uname -r

Check Version:

uname -r

Verify Fix Applied:

Verify kernel version is updated beyond patched commits. Check /var/log/kern.log for absence of ALSA HDA related crashes.

📡 Detection & Monitoring

Log Indicators:

Kernel panic messages
ALSA HDA error logs
null pointer dereference in kernel logs

Network Indicators:

None - local vulnerability only

SIEM Query:

source="kernel" AND ("ALSA" OR "HDA" OR "null pointer" OR "kernel panic")

📊 Metadata

CVE ID: CVE-2023-52806

CVSS v3 Score: 5.5 (MEDIUM)

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

CWE: CWE-476

Published: May 21, 2024

Last Updated: November 21, 2024

🔗 References

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