CVE-2025-38734 – This CVE describes a use-after-free vulnerabili... (How to Fix)

Q: What is the severity of CVE-2025-38734?

CVE-2025-38734 has a CVSS score of 7.8 (HIGH). This CVE describes a use-after-free vulnerability in the Linux kernel's SMC (Shared Memory Communications) subsystem. The vulnerability allows an attacker to cause a kernel NULL pointer dereference, potentially leading to denial of service or kernel memory corruption. Systems running affected Linux kernel versions with SMC enabled are vulnerable.

📋 TL;DR

This CVE describes a use-after-free vulnerability in the Linux kernel's SMC (Shared Memory Communications) subsystem. The vulnerability allows an attacker to cause a kernel NULL pointer dereference, potentially leading to denial of service or kernel memory corruption. Systems running affected Linux kernel versions with SMC enabled are vulnerable.

💻 Affected Systems

Products:

Linux kernel

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

Operating Systems: Linux distributions using affected kernel versions

Default Config Vulnerable: ✅ No

Notes: Only vulnerable if SMC (Shared Memory Communications) is enabled and in use. Many distributions don't enable SMC 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 →

⚠️ Risk & Real-World Impact

🔴

Worst Case

Kernel panic leading to system crash and denial of service, with potential for privilege escalation if combined with other vulnerabilities.

🟠

Likely Case

System crash or kernel panic causing denial of service, requiring system reboot.

🟢

If Mitigated

Minor performance impact if SMC is disabled or patched.

🌐 Internet-Facing: MEDIUM - Requires network access to SMC sockets, but SMC is typically used in specialized high-performance computing environments rather than general internet services.

🏢 Internal Only: MEDIUM - Internal attackers with network access to SMC services could trigger the vulnerability.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ✅ No

Complexity: MEDIUM

Exploitation requires network access to trigger the specific race condition during socket operations. The vulnerability was discovered through BPF CI testing.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Check kernel git commits: 070b4af44c4b6e4c35fb1ca7001a6a88fd2d318f, 2e765ba0ee0eae35688b443e97108308a716773e, 85545f1525f9fa9bf44fec77ba011024f15da342, d9cef55ed49117bd63695446fb84b4b91815c0b4

Vendor Advisory: https://git.kernel.org/stable/c/070b4af44c4b6e4c35fb1ca7001a6a88fd2d318f

Restart Required: Yes

Instructions:

1. Update to a kernel version containing the fix commits. 2. Reboot the system. 3. Verify the kernel version after reboot.

🔧 Temporary Workarounds

Disable SMC module

linux

Prevent loading of the SMC kernel module to mitigate the vulnerability

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

Blacklist SMC module

linux

Blacklist the SMC module to prevent automatic loading

echo 'blacklist smc' >> /etc/modprobe.d/blacklist-smc.conf

🧯 If You Can't Patch

Disable SMC functionality if not required
Implement network segmentation to restrict access to SMC services

🔍 How to Verify

Check if Vulnerable:

Check if SMC module is loaded: lsmod | grep smc. If loaded and kernel version is vulnerable, system is at risk.

Check Version:

uname -r

Verify Fix Applied:

Verify kernel version includes fix commits and SMC module functions normally without crashes.

📡 Detection & Monitoring

Log Indicators:

Kernel panic messages
NULL pointer dereference errors in kernel logs
SMC-related crash reports in dmesg

Network Indicators:

Unexpected SMC socket connections followed by disconnections

SIEM Query:

source="kernel" AND ("NULL pointer dereference" OR "smc_listen_work" OR "SMC_STAT_SERV_SUCC_INC")

📊 Metadata

CVE ID: CVE-2025-38734

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: 0.02% exploit probability (3.1th percentile)

Published: September 5, 2025

Last Updated: November 25, 2025

🔗 References

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🔗 Related Vulnerabilities

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