CVE-2023-52705

Q: What is the severity of CVE-2023-52705?

CVE-2023-52705 has a CVSS score of 5.5 (MEDIUM). A vulnerability in the Linux kernel's nilfs2 filesystem allows underflow in superblock position calculations when using devices smaller than 4096 bytes. This can cause out-of-bounds memory access during mounting or filesystem resizing operations, potentially leading to denial of service or system hangs. Systems using nilfs2 filesystem on small block devices are affected.

5.5 MEDIUM

📋 TL;DR

A vulnerability in the Linux kernel's nilfs2 filesystem allows underflow in superblock position calculations when using devices smaller than 4096 bytes. This can cause out-of-bounds memory access during mounting or filesystem resizing operations, potentially leading to denial of service or system hangs. Systems using nilfs2 filesystem on small block devices are affected.

💻 Affected Systems

Products:

Linux kernel

Versions: Kernel versions with nilfs2 support before fixes were applied (specific versions in stable patches)

Operating Systems: Linux distributions using affected kernel versions

Default Config Vulnerable: ✅ No

Notes: Only affects systems using nilfs2 filesystem on block devices smaller than 4096 bytes or during resize operations to sizes below 4096 bytes.

📦 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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⚠️ Risk & Real-World Impact

🔴

Worst Case

System becomes unresponsive due to semaphore deadlock, requiring hard reboot and potentially causing filesystem corruption.

🟠

Likely Case

Mount failure or resize operation hangs, causing denial of service for affected filesystem operations.

🟢

If Mitigated

Filesystem operations fail gracefully with error messages instead of hanging.

🌐 Internet-Facing: LOW - Requires local filesystem access and specific nilfs2 operations.

🏢 Internal Only: MEDIUM - Can affect systems where nilfs2 is used on small block devices or during resize operations.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: NO

Unauthenticated Exploit: ✅ No

Complexity: MEDIUM

Requires local access and ability to mount nilfs2 filesystems or perform resize operations on small block devices.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Multiple stable kernel patches (see references for specific commits)

Vendor Advisory: https://git.kernel.org/stable/c/0ee5ed0126a2211f7174492da2ca2c29f43755c5

Restart Required: Yes

Instructions:

1. Update Linux kernel to version containing fixes. 2. Check kernel changelog for nilfs2 fixes. 3. Reboot system after kernel update.

🔧 Temporary Workarounds

Avoid small nilfs2 devices

linux

Do not use nilfs2 filesystem on block devices smaller than 4096 bytes

Disable nilfs2 module

linux

Prevent nilfs2 module from loading if not needed

echo 'blacklist nilfs2' >> /etc/modprobe.d/blacklist.conf

🧯 If You Can't Patch

Avoid using nilfs2 filesystem on any block devices
Ensure all nilfs2 filesystems are on devices larger than 4096 bytes and avoid resize operations

🔍 How to Verify

Check if Vulnerable:

Check kernel version and if nilfs2 is in use on small block devices (<4096 bytes)

Check Version:

uname -r

Verify Fix Applied:

Verify kernel version includes nilfs2 fixes from referenced commits

📡 Detection & Monitoring

Log Indicators:

I/O error messages mentioning nilfs2 and secondary superblock
Kernel hung task warnings with nilfs2 segctord thread
Resize operation failures on nilfs2 filesystems

SIEM Query:

kernel: "NILFS.*unable to read secondary superblock" OR kernel: "task segctord.*blocked"

📊 Metadata

CVE ID: CVE-2023-52705

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-191

Published: May 21, 2024

Last Updated: December 31, 2024

📋 TL;DR

💻 Affected Systems

📦 What is this software?

Linux Kernel by Linux

Linux Kernel by Linux

Linux Kernel by Linux

Linux Kernel by Linux

Linux Kernel by Linux

Linux Kernel by Linux

Linux Kernel by Linux

Linux Kernel by Linux

Linux Kernel by Linux

Linux Kernel by Linux

Linux Kernel by Linux

Linux Kernel by Linux

Linux Kernel by Linux

Linux Kernel by Linux

⚠️ Risk & Real-World Impact

Worst Case

Likely Case

If Mitigated

🎯 Exploit Status

🛠️ Fix & Mitigation

✅ Official Fix

Instructions:

🔧 Temporary Workarounds

Avoid small nilfs2 devices

Disable nilfs2 module

🧯 If You Can't Patch

🔍 How to Verify

Check if Vulnerable:

Check Version:

Verify Fix Applied:

📡 Detection & Monitoring

Log Indicators:

SIEM Query:

📊 Metadata

🔗 References

📤 Share & Export

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