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CVE-2023-42753

7.0 HIGH
Denial of Service

📋 TL;DR

This CVE-2023-42753 is an array indexing vulnerability in the Linux kernel's netfilter subsystem that allows local attackers to perform out-of-bounds memory writes. Attackers can crash the system or potentially escalate privileges to gain root access. Only Linux systems with affected kernel versions are vulnerable.

💻 Affected Systems

Products:
  • Linux kernel
Versions: Specific affected versions vary by distribution; generally kernels before fixes in late 2023.
Operating Systems: Linux distributions including RHEL, CentOS, Fedora, Ubuntu, Debian
Default Config Vulnerable: ⚠️ Yes
Notes: Requires netfilter subsystem to be enabled (default in most configurations).

📦 What is this software?

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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

Local privilege escalation to root, allowing complete system compromise and persistence.

🟠

Likely Case

Kernel panic leading to system crash and denial of service.

🟢

If Mitigated

No impact if patched or if exploit attempts are blocked by security controls.

🌐 Internet-Facing: LOW - Requires local access to exploit.
🏢 Internal Only: HIGH - Local users or compromised accounts can exploit this vulnerability.

🎯 Exploit Status

Public PoC: ✅ No
Weaponized: UNKNOWN
Unauthenticated Exploit: ✅ No
Complexity: MEDIUM

Requires local access and kernel knowledge to exploit reliably.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Varies by distribution; check vendor advisories for specific fixed versions.

Vendor Advisory: https://access.redhat.com/errata/RHSA-2023:7370

Restart Required: Yes

Instructions:

1. Update kernel package using your distribution's package manager. 2. Reboot the system to load the new kernel.

🔧 Temporary Workarounds

Disable affected netfilter modules

linux

Unload vulnerable netfilter kernel modules if not required.

modprobe -r nf_tables
modprobe -r nfnetlink

🧯 If You Can't Patch

  • Restrict local user access and implement least privilege principles.
  • Monitor for kernel crash logs and unusual privilege escalation attempts.

🔍 How to Verify

Check if Vulnerable:

Check kernel version against vendor advisories: uname -r

Check Version:

uname -r

Verify Fix Applied:

Verify kernel version matches patched version from vendor advisory.

📡 Detection & Monitoring

Log Indicators:

  • Kernel panic messages in /var/log/messages or dmesg
  • Unexpected privilege escalation in audit logs

Network Indicators:

  • None - local exploit only

SIEM Query:

Search for 'kernel panic' or 'segfault' in kernel logs from non-scheduled reboots.

📊 Metadata

CVE ID: CVE-2023-42753
CVSS v3 Score: 7.0 (HIGH)
CVSS Vector: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
CWE: CWE-787
Published: September 25, 2023
Last Updated: November 21, 2024

🔗 References

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