CVE-2024-50286 – This is a use-after-free vulnerability in the L... (How to Fix)

Q: What is the severity of CVE-2024-50286?

CVE-2024-50286 has a CVSS score of 7.0 (HIGH). This is a use-after-free vulnerability in the Linux kernel's ksmbd SMB server module caused by a race condition between session creation and expiration functions. Attackers could potentially exploit this to crash the kernel or execute arbitrary code. Systems running affected Linux kernel versions with ksmbd enabled are vulnerable.

📋 TL;DR

This is a use-after-free vulnerability in the Linux kernel's ksmbd SMB server module caused by a race condition between session creation and expiration functions. Attackers could potentially exploit this to crash the kernel or execute arbitrary code. Systems running affected Linux kernel versions with ksmbd enabled are vulnerable.

💻 Affected Systems

Products:

Linux kernel with ksmbd module

Versions: Specific affected versions not explicitly stated in CVE, but patches exist for multiple stable branches

Operating Systems: Linux distributions using vulnerable kernel versions

Default Config Vulnerable: ✅ No

Notes: Only vulnerable if ksmbd module is loaded and active. 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 →

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

Kernel panic leading to system crash or potential arbitrary code execution with kernel privileges, resulting in complete system compromise.

🟠

Likely Case

Kernel crash causing denial of service, potentially requiring system reboot to restore functionality.

🟢

If Mitigated

No impact if ksmbd module is not loaded or if proper kernel hardening prevents exploitation.

🌐 Internet-Facing: MEDIUM - SMB services exposed to internet could be targeted, but exploitation requires specific race condition timing.

🏢 Internal Only: MEDIUM - Internal attackers with network access to SMB shares could attempt exploitation.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ✅ No

Complexity: HIGH

Exploitation requires race condition timing and SMB session access. No public exploits known at this time.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Multiple stable kernel versions with fixes: 0a77715db226, e7a2ad204437, e923503a56b3, f56446ba5378

Vendor Advisory: https://lists.debian.org/debian-lts-announce/2025/01/msg00001.html

Restart Required: Yes

Instructions:

1. Update Linux kernel to patched version from your distribution. 2. Reboot system to load new kernel. 3. Verify ksmbd module version matches patched kernel.

🔧 Temporary Workarounds

Disable ksmbd module

linux

Unload ksmbd kernel module if not required

sudo rmmod ksmbd
echo 'blacklist ksmbd' | sudo tee /etc/modprobe.d/ksmbd-blacklist.conf

Restrict SMB access

linux

Limit network access to SMB services using firewall rules

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

🧯 If You Can't Patch

Disable ksmbd module if SMB server functionality is not required
Implement strict network segmentation to limit access to SMB services

🔍 How to Verify

Check if Vulnerable:

Check if ksmbd module is loaded: lsmod | grep ksmbd. If loaded, check kernel version against patched versions.

Check Version:

uname -r

Verify Fix Applied:

Verify kernel version is updated and ksmbd module version matches patched kernel. Check dmesg for any ksmbd-related crashes.

📡 Detection & Monitoring

Log Indicators:

Kernel panic messages in dmesg
ksmbd crash logs in system logs
Unexpected system reboots

Network Indicators:

Multiple failed SMB connection attempts followed by system instability
Unusual SMB traffic patterns

SIEM Query:

source="kernel" AND ("panic" OR "Oops" OR "ksmbd")

📊 Metadata

CVE ID: CVE-2024-50286

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-416

Published: November 19, 2024

Last Updated: November 3, 2025

🔗 References

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🔗 Related Vulnerabilities

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