CVE-2023-52925 – A race condition vulnerability in the Linux ker... (How to Fix)

Q: What is the severity of CVE-2023-52925?

CVE-2023-52925 has a CVSS score of 5.5 (MEDIUM). A race condition vulnerability in the Linux kernel's netfilter nf_tables subsystem allows duplicate expired entries to be incorrectly handled during set operations. This can lead to kernel crashes or denial of service conditions. Systems running vulnerable Linux kernel versions with nf_tables enabled are affected.

📋 TL;DR

A race condition vulnerability in the Linux kernel's netfilter nf_tables subsystem allows duplicate expired entries to be incorrectly handled during set operations. This can lead to kernel crashes or denial of service conditions. Systems running vulnerable Linux kernel versions with nf_tables enabled are affected.

💻 Affected Systems

Products:

Linux Kernel

Versions: Specific vulnerable versions not explicitly stated in CVE, but patches exist in stable kernel trees. Likely affects multiple kernel versions before fixes were backported.

Operating Systems: Linux distributions using affected kernel versions

Default Config Vulnerable: ✅ No

Notes: Only vulnerable if nf_tables subsystem is enabled and in use. Many distributions may have it disabled by default or not use the specific set operations that trigger the bug.

📦 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 →

⚠️ Risk & Real-World Impact

🔴

Worst Case

Kernel panic leading to system crash and denial of service, potentially requiring physical access to reboot affected systems.

🟠

Likely Case

System instability, kernel crashes, or denial of service affecting network filtering capabilities.

🟢

If Mitigated

Minimal impact if nf_tables is not in use or proper kernel hardening measures are implemented.

🌐 Internet-Facing: MEDIUM - Could be exploited to crash network filtering systems, but requires specific conditions and kernel access.

🏢 Internal Only: MEDIUM - Similar impact internally, but exploitation requires local or network access to affected systems.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ✅ No

Complexity: HIGH

Exploitation requires kernel-level access and specific nf_tables operations. The vulnerability appears to be a race condition discovered through selftest failures, making reliable exploitation challenging.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Multiple stable kernel versions with commits: 156369a702c33ad5434a19c3a689bfb836d4e0b8, 59ee68c437c562170265194a99698c805a686bb3, 7845914f45f066497ac75b30c50dbc735e84e884, 891ca5dfe3b718b441fc786014a7ba8f517da188, af78b0489e8898a8c9449ffc0fdd2e181916f0d4

Vendor Advisory: https://git.kernel.org/stable/c/156369a702c33ad5434a19c3a689bfb836d4e0b8

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 matches patched release.

🔧 Temporary Workarounds

Disable nf_tables

linux

Disable the nf_tables subsystem if not required for your use case

modprobe -r nf_tables
echo 'blacklist nf_tables' > /etc/modprobe.d/disable-nftables.conf

Use legacy iptables

linux

Switch to legacy iptables instead of nftables for firewall rules

systemctl stop nftables
systemctl disable nftables
apt-get install iptables
yum install iptables-services

🧯 If You Can't Patch

Implement strict access controls to prevent unauthorized users from modifying nf_tables rules
Monitor system logs for kernel panic or crash events and implement automated alerting

🔍 How to Verify

Check if Vulnerable:

Check if nf_tables module is loaded: lsmod | grep nf_tables. If loaded and kernel version is unpatched, system may be vulnerable.

Check Version:

uname -r

Verify Fix Applied:

Check kernel version against patched releases from your distribution. Verify nf_tables functionality with test rules.

📡 Detection & Monitoring

Log Indicators:

Kernel panic messages in /var/log/kern.log or dmesg
nf_tables related error messages
System crash/reboot events

Network Indicators:

Unexpected firewall rule changes
Network filtering inconsistencies

SIEM Query:

source="kern.log" AND ("kernel panic" OR "nf_tables" OR "Oops")

📊 Metadata

CVE ID: CVE-2023-52925

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

EPSS Score: 0.04% exploit probability (11.1th percentile)

Published: February 5, 2025

Last Updated: October 15, 2025

🔗 References

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