CVE-2024-40939 – This CVE describes a use-after-free vulnerabili... (How to Fix)

Q: What is the severity of CVE-2024-40939?

CVE-2024-40939 has a CVSS score of 7.8 (HIGH). This CVE describes a use-after-free vulnerability in the Linux kernel's WWAN IOSM driver where a pointer is incorrectly handled when region creation fails. This could allow local attackers to potentially execute arbitrary code or cause denial of service. The vulnerability affects Linux systems using the IOSM WWAN driver.

📋 TL;DR

This CVE describes a use-after-free vulnerability in the Linux kernel's WWAN IOSM driver where a pointer is incorrectly handled when region creation fails. This could allow local attackers to potentially execute arbitrary code or cause denial of service. The vulnerability affects Linux systems using the IOSM WWAN driver.

💻 Affected Systems

Products:

Linux kernel

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

Operating Systems: Linux distributions using vulnerable kernel versions

Default Config Vulnerable: ⚠️ Yes

Notes: Requires the IOSM WWAN driver to be loaded/enabled. Not all Linux systems use 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 →

⚠️ Risk & Real-World Impact

🔴

Worst Case

Local privilege escalation to kernel-level code execution, potentially leading to full system compromise.

🟠

Likely Case

Kernel panic or system crash causing denial of service.

🟢

If Mitigated

Limited impact if proper kernel hardening and privilege separation are implemented.

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

🏢 Internal Only: MEDIUM - Could be exploited by malicious local users or through other local attack vectors.

🎯 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: Multiple stable kernel versions with fixes available (see git commits in references)

Vendor Advisory: https://git.kernel.org/stable/c/040d9384870386eb5dc55472ac573ac7756b2050

Restart Required: Yes

Instructions:

1. Update Linux kernel to patched version. 2. Reboot system. 3. Verify kernel version matches patched release.

🔧 Temporary Workarounds

Disable IOSM WWAN driver

linux

Prevent loading of the vulnerable driver module

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

🧯 If You Can't Patch

Restrict local user access to systems using the vulnerable driver
Implement strict privilege separation and limit user capabilities

🔍 How to Verify

Check if Vulnerable:

Check if IOSM driver is loaded: lsmod | grep iosm. Check kernel version against patched releases.

Check Version:

uname -r

Verify Fix Applied:

Verify kernel version is updated to patched version and IOSM driver is either updated or disabled.

📡 Detection & Monitoring

Log Indicators:

Kernel oops messages
System crashes related to WWAN/IOSM
Unexpected kernel panics

Network Indicators:

None - local vulnerability only

SIEM Query:

Search for kernel panic logs or module loading failures related to iosm/wwan

📊 Metadata

CVE ID: CVE-2024-40939

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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