CVE-2023-44466 – A buffer overflow vulnerability in the Linux ke... (How to Fix)

Q: What is the severity of CVE-2023-44466?

CVE-2023-44466 has a CVSS score of 8.8 (HIGH). A buffer overflow vulnerability in the Linux kernel's Ceph messenger component allows remote attackers to execute arbitrary code via specially crafted TCP packets. This affects Linux systems running kernel versions before 6.4.5 that have Ceph client or server functionality enabled. The vulnerability stems from improper validation of untrusted length values from network packets.

📋 TL;DR

A buffer overflow vulnerability in the Linux kernel's Ceph messenger component allows remote attackers to execute arbitrary code via specially crafted TCP packets. This affects Linux systems running kernel versions before 6.4.5 that have Ceph client or server functionality enabled. The vulnerability stems from improper validation of untrusted length values from network packets.

💻 Affected Systems

Products:

Linux kernel

Versions: All versions before 6.4.5

Operating Systems: Linux distributions using affected kernel versions

Default Config Vulnerable: ✅ No

Notes: Only vulnerable if Ceph client or server functionality is enabled/loaded. Many distributions don't enable Ceph 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 →

⚠️ Risk & Real-World Impact

🔴

Worst Case

Remote unauthenticated attacker gains full root privileges on affected systems, leading to complete system compromise, data exfiltration, and lateral movement.

🟠

Likely Case

Remote code execution with kernel privileges, allowing attackers to install persistent backdoors, manipulate data, or disrupt services.

🟢

If Mitigated

Systems without Ceph functionality or with proper network segmentation experience no impact.

🌐 Internet-Facing: HIGH - Exploitation requires only network access to Ceph services, which could be exposed to the internet in cloud or storage deployments.

🏢 Internal Only: MEDIUM - Internal systems with Ceph services remain vulnerable to internal attackers or compromised systems within the network.

🎯 Exploit Status

Public PoC: ⚠️ Yes

Weaponized: LIKELY

Unauthenticated Exploit: ⚠️ Yes

Complexity: LOW

Proof-of-concept code is publicly available in security research repositories. The vulnerability requires sending specially crafted HELLO or AUTH frames to Ceph services.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Linux kernel 6.4.5 and later

Vendor Advisory: https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=a282a2f10539dce2aa619e71e1817570d557fc97

Restart Required: Yes

Instructions:

1. Update Linux kernel to version 6.4.5 or later. 2. For distributions: Use package manager (apt/yum/dnf) to update kernel package. 3. Reboot system to load new kernel.

🔧 Temporary Workarounds

Disable Ceph module

linux

Unload Ceph kernel module if not required

modprobe -r ceph
echo 'blacklist ceph' >> /etc/modprobe.d/blacklist.conf

Network segmentation

linux

Restrict access to Ceph services (port 6789 typically)

iptables -A INPUT -p tcp --dport 6789 -j DROP
firewall-cmd --permanent --remove-port=6789/tcp

🧯 If You Can't Patch

Implement strict network access controls to isolate Ceph services from untrusted networks.
Monitor for unusual network traffic patterns or connection attempts to Ceph ports.

🔍 How to Verify

Check if Vulnerable:

Check kernel version with 'uname -r' and verify if Ceph module is loaded with 'lsmod | grep ceph'.

Check Version:

uname -r

Verify Fix Applied:

After patching, verify kernel version is 6.4.5+ and test Ceph functionality remains operational.

📡 Detection & Monitoring

Log Indicators:

Kernel panic logs
Ceph service crashes
Unexpected process creation with elevated privileges

Network Indicators:

Unusual TCP packets to Ceph ports (6789)
Malformed HELLO/AUTH frames in network captures

SIEM Query:

source="kernel" AND ("panic" OR "Oops") OR destination_port=6789 AND (payload_size>normal OR malformed_packet)

📊 Metadata

CVE ID: CVE-2023-44466

CVSS v3 Score: 8.8 (HIGH)

CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CWE: CWE-120

Published: September 29, 2023

Last Updated: May 23, 2025

🔗 References

https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=a282a2f10539dce2aa619e71e1817570d557fc97 Mailing List,Patch
https://github.com/google/security-research/security/advisories/GHSA-jg27-jx6w-xwph Exploit,Third Party Advisory
https://github.com/torvalds/linux/commit/a282a2f10539dce2aa619e71e1817570d557fc97 Patch
https://security.netapp.com/advisory/ntap-20231116-0003/ Third Party Advisory
https://www.spinics.net/lists/ceph-devel/msg57909.html Mailing List,Patch
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=a282a2f10539dce2aa619e71e1817570d557fc97 Mailing List,Patch
https://github.com/google/security-research/security/advisories/GHSA-jg27-jx6w-xwph Exploit,Third Party Advisory
https://github.com/torvalds/linux/commit/a282a2f10539dce2aa619e71e1817570d557fc97 Patch
https://security.netapp.com/advisory/ntap-20231116-0003/ Third Party Advisory
https://www.spinics.net/lists/ceph-devel/msg57909.html Mailing List,Patch

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