CVE-2025-38461 – A race condition vulnerability in the Linux ker... (How to Fix)

Q: What is the severity of CVE-2025-38461?

CVE-2025-38461 has a CVSS score of 4.7 (MEDIUM). A race condition vulnerability in the Linux kernel's vsock subsystem allows a local attacker to cause a use-after-free condition when transport modules are being unloaded. This can lead to kernel crashes (denial of service) or potentially kernel memory corruption. The vulnerability affects Linux systems using vsock (virtual socket) functionality.

📋 TL;DR

A race condition vulnerability in the Linux kernel's vsock subsystem allows a local attacker to cause a use-after-free condition when transport modules are being unloaded. This can lead to kernel crashes (denial of service) or potentially kernel memory corruption. The vulnerability affects Linux systems using vsock (virtual socket) functionality.

💻 Affected Systems

Products:

Linux kernel

Versions: Specific affected versions not explicitly stated in CVE, but patches are available in stable kernel trees. Likely affects multiple recent kernel versions with vsock support.

Operating Systems: Linux distributions using affected kernel versions

Default Config Vulnerable: ⚠️ Yes

Notes: Requires vsock functionality to be used. Common in virtualization environments (Docker, Kubernetes, VMware, etc.) and containerized applications.

📦 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...

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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 →

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 and denial of service, with potential for kernel memory corruption that could be leveraged for privilege escalation.

🟠

Likely Case

System crash or kernel panic causing denial of service on affected systems when vsock transport modules are loaded/unloaded during connection attempts.

🟢

If Mitigated

Minor performance impact from additional locking, with no security impact when patched.

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

🏢 Internal Only: MEDIUM - Local users or processes could trigger the vulnerability, potentially causing system instability.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ✅ No

Complexity: MEDIUM

Requires local access and timing to trigger the race condition. The vulnerability is a TOCTOU (Time-of-Check Time-of-Use) race condition.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Patches available in stable kernel trees via the provided git commits

Vendor Advisory: https://git.kernel.org/stable/c/36a439049b34cca0b3661276049b84a1f76cc21a

Restart Required: Yes

Instructions:

1. Update to a patched kernel version from your distribution vendor. 2. Apply the specific kernel patches from the git references. 3. Reboot the system to load the new kernel.

🔧 Temporary Workarounds

Disable vsock module

linux

Prevent loading of vsock transport modules if not required

modprobe -r vmw_vsock_virtio_transport
modprobe -r vmw_vsock_virtio_transport_common
modprobe -r vsock

Blacklist vsock modules

linux

Prevent automatic loading of vsock modules

echo 'blacklist vmw_vsock_virtio_transport' >> /etc/modprobe.d/blacklist-vsock.conf
echo 'blacklist vmw_vsock_virtio_transport_common' >> /etc/modprobe.d/blacklist-vsock.conf
echo 'blacklist vsock' >> /etc/modprobe.d/blacklist-vsock.conf

🧯 If You Can't Patch

Restrict local user access to systems using vsock functionality
Monitor for kernel panic/crash events and investigate vsock-related processes

🔍 How to Verify

Check if Vulnerable:

Check kernel version and if vsock modules are loaded: lsmod | grep vsock

Check Version:

uname -r

Verify Fix Applied:

Verify kernel version is updated and check dmesg for vsock-related errors after patch

📡 Detection & Monitoring

Log Indicators:

Kernel panic messages in dmesg/system logs
Page fault errors mentioning vsock_assign_transport
System crashes with vsock in call trace

Network Indicators:

Unusual vsock connection attempts from local processes

SIEM Query:

source="kernel" AND ("vsock" OR "transport_" OR "page fault" OR "Oops")

📊 Metadata

CVE ID: CVE-2025-38461

CVSS v3 Score: 4.7 (MEDIUM)

CVSS Vector: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H

CWE: CWE-367

EPSS Score: 0.01% exploit probability (2.3th percentile)

Published: July 25, 2025

Last Updated: December 22, 2025

🔗 References

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