CVE-2024-50086 – This CVE describes a use-after-free vulnerabili... (How to Fix)

Q: What is the severity of CVE-2024-50086?

CVE-2024-50086 has a CVSS score of 7.0 (HIGH). This CVE describes a use-after-free vulnerability in the Linux kernel's ksmbd (SMB server) module. It allows an attacker to potentially crash the kernel or execute arbitrary code by exploiting a race condition between session logoff and setup operations. Systems running affected Linux kernel versions with ksmbd enabled are vulnerable.

📋 TL;DR

This CVE describes a use-after-free vulnerability in the Linux kernel's ksmbd (SMB server) module. It allows an attacker to potentially crash the kernel or execute arbitrary code by exploiting a race condition between session logoff and setup operations. 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 description; check kernel commit references for exact ranges

Operating Systems: Linux distributions with vulnerable 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 →

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

Limited impact if ksmbd is disabled or proper access controls restrict SMB connections to trusted sources only.

🌐 Internet-Facing: MEDIUM - Exploitation requires SMB access, which is often firewalled externally but could be exposed in some configurations.

🏢 Internal Only: HIGH - Internal attackers with network access to SMB services could exploit this vulnerability to crash systems or potentially gain elevated privileges.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ✅ No

Complexity: MEDIUM

Exploitation requires SMB session establishment and timing precision for race condition. No public exploit code identified at this time.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Kernel versions containing commits: 0f62358ce85b2d4c949ef1b648be01b29cec667a, 5511999e9615e4318e9142d23b29bd1597befc08, 7aa8804c0b67b3cb263a472d17f2cb50d7f1a930, a9839c37fd813b432988f58a9d9dd59253d3eb2c, ee371898b53a9b9b51c02d22a8c31bfb86d45f0d

Vendor Advisory: https://git.kernel.org/stable/c/0f62358ce85b2d4c949ef1b648be01b29cec667a

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 required.

🔧 Temporary Workarounds

Disable ksmbd module

linux

Prevent loading of vulnerable ksmbd kernel module

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

Restrict SMB network access

linux

Use firewall rules to limit SMB connections to trusted sources only

iptables -A INPUT -p tcp --dport 445 -s trusted_network -j ACCEPT
iptables -A INPUT -p tcp --dport 445 -j DROP

🧯 If You Can't Patch

Disable ksmbd module if not required for business operations
Implement strict network segmentation to isolate SMB services from untrusted networks

🔍 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 includes the fix commits and ksmbd module loads without errors.

📡 Detection & Monitoring

Log Indicators:

Kernel panic messages
ksmbd crash logs in dmesg or journalctl
Unexpected SMB session termination

Network Indicators:

Multiple rapid SMB session establishment/logoff attempts
Unusual SMB traffic patterns

SIEM Query:

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

📊 Metadata

CVE ID: CVE-2024-50086

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: October 29, 2024

Last Updated: November 3, 2025

🔗 References

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🔗 Related Vulnerabilities

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