CVE-2025-38666

7.8 HIGH

📋 TL;DR

A race condition in the Linux kernel's Appletalk AARP proxy-probe routine allows a use-after-free vulnerability when an expire timer thread frees memory that is still being accessed. This can lead to kernel memory corruption, crashes, or potential privilege escalation. Systems running vulnerable Linux kernel versions with Appletalk support are affected.

💻 Affected Systems

Products:

Linux kernel

Versions: Specific vulnerable versions not explicitly stated, but references indicate stable kernel patches.

Operating Systems: Linux distributions using vulnerable kernel versions

Default Config Vulnerable: ✅ No

Notes: Requires Appletalk (CONFIG_ATALK) kernel module loaded or built-in, which is typically disabled by default in modern distributions.

📦 What is this software?

Debian Linux by Debian

View all CVEs affecting Debian Linux →

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...

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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 →

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, or potential privilege escalation to root via kernel memory corruption.

🟠

Likely Case

Kernel crash or system instability due to memory corruption.

🟢

If Mitigated

Limited impact if Appletalk is disabled or not in use.

🌐 Internet-Facing: LOW - Appletalk is a legacy Apple networking protocol rarely exposed externally.

🏢 Internal Only: MEDIUM - Requires local access or network access to Appletalk services, which are uncommon in modern networks.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ✅ No

Complexity: HIGH - Requires race condition timing and Appletalk network access.

Exploitation requires triggering the race condition between proxy-probe and expire timer threads.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Patched in kernel commits: 186942d19c0222617ef61f50e1dba91e269a5963, 2a6209e4649d45fd85d4193abc481911858ffc6f, 5f02ea0f63dd38c41539ea290fcc1693c73aa8e5, 6c4a92d07b0850342d3becf2e608f805e972467c, 82d19a70ced28b17a38ebf1b6978c6c7db894979

Vendor Advisory: https://git.kernel.org/stable/c/186942d19c0222617ef61f50e1dba91e269a5963

Restart Required: Yes

Instructions:

1. Update Linux kernel to a patched version from your distribution vendor. 2. Reboot the system to load the new kernel.

🔧 Temporary Workarounds

Disable Appletalk kernel module

linux

Prevent loading of the vulnerable Appletalk module.

echo 'blacklist appletalk' >> /etc/modprobe.d/blacklist.conf
rmmod appletalk

Disable Appletalk at kernel build

linux

Build kernel without Appletalk support (CONFIG_ATALK=n).

🧯 If You Can't Patch

Disable Appletalk kernel module if not needed.
Restrict network access to Appletalk services using firewall rules.

🔍 How to Verify

Check if Vulnerable:

Check if Appletalk module is loaded: lsmod | grep appletalk

Check Version:

uname -r

Verify Fix Applied:

Check kernel version against patched versions from your distribution.

📡 Detection & Monitoring

Log Indicators:

Kernel panic logs
KASAN use-after-free reports in dmesg

Network Indicators:

Appletalk (DDP/AARP) network traffic on ports 201-202, 204

SIEM Query:

Search for kernel crash logs or Appletalk-related errors in system logs.

📊 Metadata

CVE ID: CVE-2025-38666

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

EPSS Score: 0.01% exploit probability (2.4th percentile)

Published: August 22, 2025

Last Updated: January 7, 2026

🔗 References