CVE-2025-38618 – A use-after-free vulnerability in the Linux ker... (How to Fix)

Q: What is the severity of CVE-2025-38618?

CVE-2025-38618 has a CVSS score of 7.8 (HIGH). A use-after-free vulnerability in the Linux kernel's vsock (virtual socket) subsystem allows local attackers to potentially escalate privileges or crash the system. The vulnerability occurs when a vsock socket binds to VMADDR_PORT_ANY, leading to improper reference counting during connection handling. This affects Linux systems using vsock functionality, particularly in virtualized environments.

📋 TL;DR

A use-after-free vulnerability in the Linux kernel's vsock (virtual socket) subsystem allows local attackers to potentially escalate privileges or crash the system. The vulnerability occurs when a vsock socket binds to VMADDR_PORT_ANY, leading to improper reference counting during connection handling. This affects Linux systems using vsock functionality, particularly in virtualized environments.

💻 Affected Systems

Products:

Linux kernel

Versions: Versions before the fix commits (specific versions vary by distribution)

Operating Systems: Linux distributions using affected kernel versions

Default Config Vulnerable: ⚠️ Yes

Notes: Requires vsock functionality to be enabled/used. More impactful in virtualized environments where vsock is commonly used.

📦 What is this software?

Debian Linux by Debian

View all CVEs affecting Debian Linux →

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

Local privilege escalation to root, kernel panic causing system crash, or potential container escape in virtualized environments.

🟠

Likely Case

Local denial of service through kernel panic or system instability.

🟢

If Mitigated

Minimal impact with proper kernel hardening and restricted user privileges.

🌐 Internet-Facing: LOW - This is a local vulnerability requiring access to the system.

🏢 Internal Only: MEDIUM - Internal users with shell access could exploit this for privilege escalation or DoS.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ✅ No

Complexity: MEDIUM

Requires local access and knowledge of vsock programming. No public exploit code known at this time.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Kernel versions containing the fix commits (32950b1907919be86a7a2697d6f93d57068b3865 and related)

Vendor Advisory: https://git.kernel.org/stable/c/32950b1907919be86a7a2697d6f93d57068b3865

Restart Required: Yes

Instructions:

1. Update Linux kernel to patched version from your distribution's repositories. 2. Reboot system to load new kernel. 3. Verify kernel version after reboot.

🔧 Temporary Workarounds

Disable vsock module

linux

Prevent loading of vsock kernel module if not required

echo 'install vsock /bin/false' >> /etc/modprobe.d/disable-vsock.conf
rmmod vsock 2>/dev/null || true

🧯 If You Can't Patch

Restrict user access to minimize attack surface
Implement kernel hardening measures like SELinux/AppArmor

🔍 How to Verify

Check if Vulnerable:

Check kernel version against distribution security advisories. Vulnerable if using unpatched kernel with vsock enabled.

Check Version:

uname -r

Verify Fix Applied:

Verify kernel version matches patched version from your distribution. Check that vsock functionality still works if needed.

📡 Detection & Monitoring

Log Indicators:

Kernel panic logs
OOM killer activity related to vsock
Unexpected system crashes

Network Indicators:

Unusual vsock connection attempts from local processes

SIEM Query:

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

📊 Metadata

CVE ID: CVE-2025-38618

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: 0.01% exploit probability (2.4th percentile)

Published: August 22, 2025

Last Updated: January 7, 2026

🔗 References

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