CVE-2023-53440 – This vulnerability in the Linux kernel's nilfs2... (How to Fix)

Q: What is the severity of CVE-2023-53440?

CVE-2023-53440 has a CVSS score of 5.5 (MEDIUM). This vulnerability in the Linux kernel's nilfs2 filesystem involves improper sysfs interface lifetime management, potentially leading to null pointer dereferences or use-after-free conditions. It affects Linux systems using the nilfs2 filesystem, primarily impacting system stability rather than remote exploitation.

📋 TL;DR

This vulnerability in the Linux kernel's nilfs2 filesystem involves improper sysfs interface lifetime management, potentially leading to null pointer dereferences or use-after-free conditions. It affects Linux systems using the nilfs2 filesystem, primarily impacting system stability rather than remote exploitation.

💻 Affected Systems

Products:

Linux kernel with nilfs2 filesystem support

Versions: Linux kernel versions before the fix commits (check specific stable branches)

Operating Systems: Linux distributions with nilfs2 enabled

Default Config Vulnerable: ✅ No

Notes: Only vulnerable if nilfs2 filesystem is actually used. Many distributions don't enable nilfs2 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 →

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 or system crash due to null pointer dereference or use-after-free when accessing sysfs attributes during metadata file operations.

🟠

Likely Case

System instability, lockdep warnings, or kernel oops when interacting with nilfs2 sysfs interfaces during filesystem operations.

🟢

If Mitigated

Minor performance impact or false positive lockdep warnings without actual system crashes.

🌐 Internet-Facing: LOW - Requires local filesystem access and specific nilfs2 operations, not remotely exploitable.

🏢 Internal Only: MEDIUM - Local users with filesystem access could trigger instability, but requires specific nilfs2 usage patterns.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ✅ No

Complexity: MEDIUM

Requires local access and specific nilfs2 operations to trigger. More likely to cause system instability than privilege escalation.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Linux kernel with commits: 1942ccb7d95f, 3dbee84bf9e3, 42560f9c92cc, 5fe0ea141fbb, 83b16a60e413

Vendor Advisory: https://git.kernel.org/stable/c/1942ccb7d95f287a312fcbabfa8bc9ba501b1953

Restart Required: Yes

Instructions:

1. Update Linux kernel to version containing the fix commits. 2. Reboot system to load new kernel. 3. Verify nilfs2 modules are updated.

🔧 Temporary Workarounds

Disable nilfs2 module

Linux

Prevent loading of nilfs2 kernel module if not needed

echo 'install nilfs2 /bin/false' >> /etc/modprobe.d/disable-nilfs2.conf
rmmod nilfs2

Avoid nilfs2 usage

all

Do not create or mount nilfs2 filesystems

🧯 If You Can't Patch

Avoid using nilfs2 filesystem for critical operations
Monitor system logs for nilfs2-related kernel warnings or crashes

🔍 How to Verify

Check if Vulnerable:

Check if nilfs2 module is loaded: lsmod | grep nilfs2. Check kernel version against patched versions.

Check Version:

uname -r

Verify Fix Applied:

Verify kernel version includes fix commits. Test nilfs2 sysfs operations after patch.

📡 Detection & Monitoring

Log Indicators:

Kernel oops messages mentioning nilfs2
Lockdep warnings with nilfs2 in call stack
System crashes during nilfs2 operations

Network Indicators:

None - local filesystem vulnerability

SIEM Query:

Search for kernel logs containing 'nilfs2' AND ('Oops' OR 'BUG' OR 'general protection fault')

📊 Metadata

CVE ID: CVE-2023-53440

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

EPSS Score: 0.01% exploit probability (1.3th percentile)

Published: September 18, 2025

Last Updated: January 14, 2026

🔗 References

📤 Share & Export

📄 Export Markdown 📋 Export JSON

🔗 Related Vulnerabilities

If you're affected by CVE-2023-53440, you might also want to check these: