CVE-2024-39371 – A NULL pointer dereference vulnerability in the... (How to Fix)

Q: What is the severity of CVE-2024-39371?

CVE-2024-39371 has a CVSS score of 5.5 (MEDIUM). A NULL pointer dereference vulnerability in the Linux kernel's io_uring subsystem allows local attackers to cause a kernel panic (denial of service) by triggering forced async preparation with a bad file descriptor. This affects Linux systems using io_uring with vulnerable kernel versions.

📋 TL;DR

A NULL pointer dereference vulnerability in the Linux kernel's io_uring subsystem allows local attackers to cause a kernel panic (denial of service) by triggering forced async preparation with a bad file descriptor. This affects Linux systems using io_uring with vulnerable kernel versions.

💻 Affected Systems

Products:

Linux kernel

Versions: Kernel versions before fixes in stable releases (specific commits: 43cfac7b88adedfb26c27834386992650f1642f3, 5fc16fa5f13b3c06fdb959ef262050bd810416a2, 65561b4c1c9e01443cb76387eb36a9109e7048ee, c2844d5e58576c55d8e8d4a9f74902d3f7be8044)

Operating Systems: Linux distributions using affected kernel versions

Default Config Vulnerable: ⚠️ Yes

Notes: Requires io_uring subsystem usage. Systems with restricted user access or without io_uring usage are less vulnerable.

📦 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 →

⚠️ Risk & Real-World Impact

🔴

Worst Case

Kernel panic leading to system crash and denial of service, potentially causing data loss or service disruption.

🟠

Likely Case

Local denial of service through kernel panic, requiring system reboot to recover.

🟢

If Mitigated

Minimal impact with proper patching - failed operations return -EBADF error instead of crashing.

🌐 Internet-Facing: LOW - requires local access to exploit, not remotely exploitable.

🏢 Internal Only: MEDIUM - local users or processes can cause system crashes, affecting availability.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ✅ No

Complexity: MEDIUM - requires understanding of io_uring and ability to trigger forced async preparation with bad file descriptors

Exploitation requires local access. The vulnerability was discovered through code analysis and fixed proactively.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Kernel versions containing the fix commits listed in references

Vendor Advisory: https://git.kernel.org/stable/c/43cfac7b88adedfb26c27834386992650f1642f3

Restart Required: Yes

Instructions:

1. Update Linux kernel to patched version from your distribution's repositories. 2. Reboot system to load new kernel. 3. Verify kernel version after reboot.

🔧 Temporary Workarounds

Disable io_uring module

linux

Prevent loading of io_uring kernel module to mitigate vulnerability

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

Restrict user access

linux

Limit system access to trusted users only to reduce attack surface

🧯 If You Can't Patch

Implement strict access controls to limit local user privileges
Monitor system logs for kernel panic events and unauthorized access attempts

🔍 How to Verify

Check if Vulnerable:

Check kernel version and compare with patched versions. Examine if system uses io_uring.

Check Version:

uname -r

Verify Fix Applied:

Verify kernel version matches patched version and test io_uring functionality

📡 Detection & Monitoring

Log Indicators:

Kernel panic messages in /var/log/kern.log or dmesg
NULL pointer dereference errors
System crash/reboot events

Network Indicators:

None - local exploitation only

SIEM Query:

source="kernel" AND ("NULL pointer dereference" OR "kernel panic" OR "Oops")

📊 Metadata

CVE ID: CVE-2024-39371

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: June 25, 2024

Last Updated: November 3, 2025

🔗 References

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🔗 Related Vulnerabilities

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