CVE-2024-26592 – This is a use-after-free vulnerability in the L... (How to Fix)

Q: What is the severity of CVE-2024-26592?

CVE-2024-26592 has a CVSS score of 7.8 (HIGH). This is a use-after-free vulnerability in the Linux kernel's ksmbd SMB server module that allows attackers to potentially crash the kernel or execute arbitrary code. It affects Linux systems running vulnerable kernel versions with ksmbd enabled. The vulnerability occurs due to a race condition during TCP connection handling.

📋 TL;DR

This is a use-after-free vulnerability in the Linux kernel's ksmbd SMB server module that allows attackers to potentially crash the kernel or execute arbitrary code. It affects Linux systems running vulnerable kernel versions with ksmbd enabled. The vulnerability occurs due to a race condition during TCP connection handling.

💻 Affected Systems

Products:

Linux kernel with ksmbd module

Versions: Linux kernel versions with vulnerable ksmbd implementation (specific versions not specified in CVE)

Operating Systems: Linux distributions using affected kernel versions

Default Config Vulnerable: ✅ No

Notes: Only vulnerable if ksmbd module is loaded and SMB services are enabled. Many distributions don't enable ksmbd 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 →

⚠️ Risk & Real-World Impact

🔴

Worst Case

Kernel panic leading to system crash or potential remote code execution with kernel privileges, allowing complete system compromise.

🟠

Likely Case

Denial of service through kernel panic or system crash, disrupting SMB file sharing services.

🟢

If Mitigated

Limited impact if ksmbd module is not loaded or SMB services are not exposed to untrusted networks.

🌐 Internet-Facing: MEDIUM - Only affects systems with ksmbd enabled and exposed to network, but requires specific race condition timing.

🏢 Internal Only: LOW - Requires network access to SMB services and successful race condition exploitation.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ⚠️ Yes

Complexity: HIGH

Exploitation requires winning a race condition, making reliable exploitation challenging but possible.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Kernel versions containing commits: 24290ba94cd0136e417283b0dbf8fcdabcf62111, 380965e48e9c32ee4263c023e1d830ea7e462ed1, 38d20c62903d669693a1869aa68c4dd5674e2544, 69d54650b751532d1e1613a4fb433e591aeef126, 999daf367b924fdf14e9d83e034ee0f86bc17ec6

Vendor Advisory: https://git.kernel.org/stable/c/24290ba94cd0136e417283b0dbf8fcdabcf62111

Restart Required: Yes

Instructions:

1. Update Linux kernel to patched version from your distribution vendor. 2. Reboot system to load new kernel. 3. Verify ksmbd module loads correctly if needed.

🔧 Temporary Workarounds

Disable ksmbd module

linux

Prevent loading of vulnerable ksmbd kernel module

echo 'blacklist ksmbd' >> /etc/modprobe.d/blacklist-ksmbd.conf
rmmod ksmbd

Block SMB ports

linux

Block SMB network access at firewall

iptables -A INPUT -p tcp --dport 445 -j DROP
iptables -A INPUT -p tcp --dport 139 -j DROP

🧯 If You Can't Patch

Disable ksmbd module if not required for operations
Implement network segmentation to restrict SMB access to trusted sources only

🔍 How to Verify

Check if Vulnerable:

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

Check Version:

uname -r

Verify Fix Applied:

Verify kernel version includes fix commits and ksmbd module loads without errors.

📡 Detection & Monitoring

Log Indicators:

Kernel panic messages
ksmbd crash logs in dmesg or journalctl
Unexpected SMB connection failures

Network Indicators:

Multiple rapid SMB connection attempts from single source
Abnormal SMB protocol traffic patterns

SIEM Query:

source="kernel" AND ("panic" OR "Oops" OR "general protection fault") AND process="ksmbd"

📊 Metadata

CVE ID: CVE-2024-26592

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

Published: February 22, 2024

Last Updated: November 21, 2024

🔗 References

📤 Share & Export

📄 Export Markdown 📋 Export JSON

🔗 Related Vulnerabilities

If you're affected by CVE-2024-26592, you might also want to check these: