CVE-2025-39713 – A race condition vulnerability in the Linux ker... (How to Fix)

Q: What is the severity of CVE-2025-39713?

CVE-2025-39713 has a CVSS score of 4.7 (MEDIUM). A race condition vulnerability in the Linux kernel's rainshadow-cec driver allows concurrent interrupt handlers to cause a buffer overflow. This affects Linux systems using the rainshadow-cec driver for HDMI-CEC functionality. The vulnerability could lead to kernel memory corruption or system instability.

📋 TL;DR

A race condition vulnerability in the Linux kernel's rainshadow-cec driver allows concurrent interrupt handlers to cause a buffer overflow. This affects Linux systems using the rainshadow-cec driver for HDMI-CEC functionality. The vulnerability could lead to kernel memory corruption or system instability.

💻 Affected Systems

Products:

Linux kernel with rainshadow-cec driver

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

Operating Systems: Linux distributions with affected kernel versions

Default Config Vulnerable: ⚠️ Yes

Notes: Only vulnerable if rainshadow-cec driver is loaded and in use (typically for HDMI-CEC functionality on compatible hardware).

📦 What is this software?

Debian Linux by Debian

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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 →

⚠️ Risk & Real-World Impact

🔴

Worst Case

Kernel memory corruption leading to system crash, denial of service, or potential privilege escalation if combined with other vulnerabilities.

🟠

Likely Case

System instability, kernel panics, or denial of service affecting HDMI-CEC functionality.

🟢

If Mitigated

Minimal impact with proper kernel hardening and isolation of affected systems.

🌐 Internet-Facing: LOW - This is a local kernel driver vulnerability requiring local access or specific hardware interaction.

🏢 Internal Only: MEDIUM - Could be exploited by local users or through malicious HDMI-CEC devices on internal networks.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ✅ No

Complexity: MEDIUM

Exploitation requires precise timing and local access to trigger the race condition. No public exploits known at this time.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Linux kernel with commits: 1c2769dc8025, 2964dbe631fd, 21ad7873b175, 3c3e33b7edca, 6aaef1a75985, 7af160aea26c

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

Restart Required: No

Instructions:

1. Update Linux kernel to version containing the fix commits. 2. For distributions: Use package manager (apt/yum/dnf) to update kernel. 3. Rebuild kernel if using custom kernel with affected code.

🔧 Temporary Workarounds

Disable rainshadow-cec driver

all

Prevent loading of the vulnerable driver module

echo 'blacklist rainshadow_cec' >> /etc/modprobe.d/blacklist.conf
rmmod rainshadow_cec

Disable HDMI-CEC functionality

all

Turn off CEC features at hardware/BIOS level if available

🧯 If You Can't Patch

Restrict local user access to systems using rainshadow-cec driver
Isolate systems with HDMI-CEC functionality from untrusted networks

🔍 How to Verify

Check if Vulnerable:

Check if rainshadow-cec module is loaded: lsmod | grep rainshadow_cec. Check kernel version against patched versions.

Check Version:

uname -r

Verify Fix Applied:

Verify kernel version includes fix commits. Check dmesg for no rain_interrupt related errors after update.

📡 Detection & Monitoring

Log Indicators:

Kernel panic messages
dmesg errors mentioning rain_interrupt or rainshadow-cec
System crashes during HDMI-CEC operations

Network Indicators:

Unusual HDMI-CEC traffic patterns if monitored

SIEM Query:

source="kernel" AND ("rainshadow" OR "rain_interrupt" OR "CEC") AND ("panic" OR "error" OR "overflow")

📊 Metadata

CVE ID: CVE-2025-39713

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 (1.3th percentile)

Published: September 5, 2025

Last Updated: January 7, 2026

🔗 References

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