CVE-2023-53311 – This is a use-after-free vulnerability in the L... (How to Fix)

Q: What is the severity of CVE-2023-53311?

CVE-2023-53311 has a CVSS score of 7.8 (HIGH). This is a use-after-free vulnerability in the Linux kernel's nilfs2 filesystem that occurs during unmount operations. It allows attackers with local access to potentially crash the system or execute arbitrary code by triggering specific inode operations. All Linux systems using the nilfs2 filesystem are affected.

📋 TL;DR

This is a use-after-free vulnerability in the Linux kernel's nilfs2 filesystem that occurs during unmount operations. It allows attackers with local access to potentially crash the system or execute arbitrary code by triggering specific inode operations. All Linux systems using the nilfs2 filesystem are affected.

💻 Affected Systems

Products:

Linux kernel with nilfs2 filesystem support

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

Operating Systems: Linux distributions with nilfs2 support

Default Config Vulnerable: ✅ No

Notes: Only vulnerable when nilfs2 filesystem is mounted and being unmounted. Most systems don't use 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 leading to denial of service, or potential privilege escalation to kernel-level code execution.

🟠

Likely Case

System crash or kernel panic causing denial of service.

🟢

If Mitigated

Limited impact if nilfs2 filesystem is not mounted or system has proper access controls.

🌐 Internet-Facing: LOW - Requires local filesystem access, not directly exploitable over network.

🏢 Internal Only: MEDIUM - Local attackers with user privileges could exploit this to crash systems or potentially escalate privileges.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ✅ No

Complexity: MEDIUM

Exploitation requires local access and specific timing during unmount operations. The vulnerability was discovered through syzbot fuzzing.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Linux kernel with commits 11afd67f1b3c28eb216e50a3ca8dbcb69bb71793 or later

Vendor Advisory: https://git.kernel.org/stable/c/11afd67f1b3c28eb216e50a3ca8dbcb69bb71793

Restart Required: Yes

Instructions:

1. Update Linux kernel to version containing the fix commit. 2. Check your distribution's security advisories for specific patched kernel versions. 3. Reboot system after kernel update.

🔧 Temporary Workarounds

Avoid nilfs2 usage

linux

Do not mount or use nilfs2 filesystems until patched

# Check for nilfs2 mounts: mount | grep nilfs2
# Unmount any nilfs2 filesystems: umount /path/to/nilfs2/mount

Disable nilfs2 kernel module

linux

Prevent nilfs2 module from loading

# Add to /etc/modprobe.d/blacklist.conf: blacklist nilfs2
# Update initramfs: update-initramfs -u

🧯 If You Can't Patch

Avoid unmounting nilfs2 filesystems while system is under load
Implement strict access controls to prevent local users from triggering unmount operations

🔍 How to Verify

Check if Vulnerable:

Check kernel version and if nilfs2 module is loaded: uname -r && lsmod | grep nilfs2

Check Version:

uname -r

Verify Fix Applied:

Verify kernel version includes fix commit: grep -q '11afd67f1b3c28eb216e50a3ca8dbcb69bb71793' /proc/version_signature (if available) or check distribution's patched kernel version

📡 Detection & Monitoring

Log Indicators:

Kernel panic messages in /var/log/kern.log or dmesg
nilfs2-related errors during unmount operations
Use-after-free kernel warnings

Network Indicators:

None - local vulnerability only

SIEM Query:

Search for kernel panic events or nilfs2 filesystem errors in system logs

📊 Metadata

CVE ID: CVE-2023-53311

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 (1.2th percentile)

Published: September 16, 2025

Last Updated: January 14, 2026

🔗 References

📤 Share & Export

📄 Export Markdown 📋 Export JSON

🔗 Related Vulnerabilities

If you're affected by CVE-2023-53311, you might also want to check these: