CVE-2025-37926 – A use-after-free vulnerability in the Linux ker... (How to Fix)

Q: What is the severity of CVE-2025-37926?

CVE-2025-37926 has a CVSS score of 7.8 (HIGH). A use-after-free vulnerability in the Linux kernel's ksmbd component allows attackers to potentially crash systems or execute arbitrary code. This affects Linux systems running vulnerable kernel versions with ksmbd enabled. Attackers need local access to exploit this race condition vulnerability.

📋 TL;DR

A use-after-free vulnerability in the Linux kernel's ksmbd component allows attackers to potentially crash systems or execute arbitrary code. This affects Linux systems running vulnerable kernel versions with ksmbd enabled. Attackers need local access to exploit this race condition vulnerability.

💻 Affected Systems

Products:

Linux kernel with ksmbd module

Versions: Specific kernel versions containing vulnerable ksmbd code (check git commits for exact ranges)

Operating Systems: Linux distributions with vulnerable kernel versions

Default Config Vulnerable: ✅ No

Notes: Only vulnerable if ksmbd (SMB server) module is loaded and 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

Local privilege escalation to kernel-level code execution, leading to complete system compromise.

🟠

Likely Case

Kernel panic or system crash causing denial of service.

🟢

If Mitigated

No impact if ksmbd is disabled or proper kernel patches are applied.

🌐 Internet-Facing: LOW - Requires local access to exploit, not directly reachable from internet.

🏢 Internal Only: MEDIUM - Local attackers or compromised accounts could exploit this vulnerability.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ✅ No

Complexity: MEDIUM

Requires local access and race condition triggering. No public exploits known at this time.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Kernel versions containing commits: 1067361a1cc6ad9cdf7acfc47f90012b72ad1502, 6323fec65fe54b365961fed260dd579191e46121, 8fb3b6c85b7e3127161623586b62abcc366caa20, a1f46c99d9ea411f9bf30025b912d881d36fc709, a4348710a7267705b75692dc1a000920481d1d92

Vendor Advisory: https://git.kernel.org/stable/c/1067361a1cc6ad9cdf7acfc47f90012b72ad1502

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 is using patched code.

🔧 Temporary Workarounds

Disable ksmbd module

linux

Prevent loading of vulnerable ksmbd module

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

Restrict local access

linux

Limit who can access SMB services locally

🧯 If You Can't Patch

Disable ksmbd module if not required for business operations
Implement strict access controls and monitoring for local users

🔍 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 shows no use-after-free in code inspection.

📡 Detection & Monitoring

Log Indicators:

Kernel panic logs
ksmbd crash messages in dmesg
UAF-related kernel oops messages

Network Indicators:

Unexpected SMB connection failures if ksmbd crashes

SIEM Query:

source="kernel" AND ("ksmbd" OR "use-after-free" OR "UAF")

📊 Metadata

CVE ID: CVE-2025-37926

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

EPSS Score: 0.03% exploit probability (7.1th percentile)

Published: May 20, 2025

Last Updated: February 6, 2026

🔗 References

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🔗 Related Vulnerabilities

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