CVE-2024-39495 – A race condition in the Linux kernel's Greybus ... (How to Fix)

Q: What is the severity of CVE-2024-39495?

CVE-2024-39495 has a CVSS score of 7.8 (HIGH). A race condition in the Linux kernel's Greybus subsystem allows a use-after-free vulnerability when interface cleanup occurs while mode switch work is still pending. This can lead to kernel memory corruption and potential privilege escalation. Systems using Greybus interfaces (common in mobile/embedded devices) are affected.

📋 TL;DR

A race condition in the Linux kernel's Greybus subsystem allows a use-after-free vulnerability when interface cleanup occurs while mode switch work is still pending. This can lead to kernel memory corruption and potential privilege escalation. Systems using Greybus interfaces (common in mobile/embedded devices) are affected.

💻 Affected Systems

Products:

Linux kernel with Greybus subsystem enabled

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

Operating Systems: Linux distributions with Greybus support

Default Config Vulnerable: ✅ No

Notes: Only vulnerable if Greybus subsystem is compiled and loaded (common in Android/mobile/embedded systems). Most desktop/server distributions don't enable Greybus by default.

📦 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

Kernel panic, system crash, or local privilege escalation to root, potentially leading to full system compromise.

🟠

Likely Case

System instability, kernel crashes, or denial of service on affected Greybus-enabled devices.

🟢

If Mitigated

Minimal impact with proper kernel hardening and restricted user access to Greybus interfaces.

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

🏢 Internal Only: MEDIUM - Local attackers or malicious processes could exploit this to escalate privileges or crash systems.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ✅ No

Complexity: MEDIUM

Requires local access and ability to trigger Greybus interface operations. Race conditions are timing-sensitive and harder to exploit reliably.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Fixed in Linux kernel stable releases via commits: 03ea2b129344, 0b8fba38bdfb, 2b6bb0b4abfd, 5c9c5d7f26ac, 74cd0a421896

Vendor Advisory: https://git.kernel.org/stable/c/03ea2b129344152157418929f06726989efc0445

Restart Required: Yes

Instructions:

1. Update Linux kernel to version containing the fix. 2. Check your distribution's security advisories. 3. Rebuild kernel if using custom build. 4. Reboot system to load patched kernel.

🔧 Temporary Workarounds

Disable Greybus module

linux

Remove or blacklist Greybus kernel module if not needed

rmmod gb_interface
echo 'blacklist greybus' >> /etc/modprobe.d/blacklist.conf

🧯 If You Can't Patch

Restrict user access to Greybus interfaces and system privileges
Implement kernel hardening (KASLR, stack protection) and monitor for crash logs

🔍 How to Verify

Check if Vulnerable:

Check kernel version and if Greybus modules are loaded: 'lsmod | grep greybus' and 'uname -r'

Check Version:

uname -r

Verify Fix Applied:

Verify kernel version includes fix commits or is newer than vulnerable versions. Check 'dmesg' for Greybus-related errors.

📡 Detection & Monitoring

Log Indicators:

Kernel panic logs
Use-after-free warnings in dmesg
Greybus interface errors

Network Indicators:

None - local vulnerability only

SIEM Query:

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

📊 Metadata

CVE ID: CVE-2024-39495

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: July 12, 2024

Last Updated: November 3, 2025

🔗 References

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🔗 Related Vulnerabilities

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