CVE-2025-39761 – A memory corruption vulnerability in the Linux ... (How to Fix)

Q: What is the severity of CVE-2025-39761?

CVE-2025-39761 has a CVSS score of 7.1 (HIGH). A memory corruption vulnerability in the Linux kernel's ath12k WiFi driver could allow out-of-bounds access when handling RX peer fragment setup errors. This affects systems using vulnerable versions of the Linux kernel with the ath12k driver enabled. Attackers could potentially crash the kernel or execute arbitrary code.

📋 TL;DR

A memory corruption vulnerability in the Linux kernel's ath12k WiFi driver could allow out-of-bounds access when handling RX peer fragment setup errors. This affects systems using vulnerable versions of the Linux kernel with the ath12k driver enabled. Attackers could potentially crash the kernel or execute arbitrary code.

💻 Affected Systems

Products:

Linux kernel with ath12k driver

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

Operating Systems: Linux distributions using vulnerable kernel versions

Default Config Vulnerable: ⚠️ Yes

Notes: Only affects systems using the ath12k WiFi driver. The vulnerability is in error handling code path, so exploitation requires triggering specific error conditions.

📦 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 →

⚠️ Risk & Real-World Impact

🔴

Worst Case

Kernel panic leading to system crash or potential arbitrary code execution with kernel privileges, resulting in complete system compromise.

🟠

Likely Case

System instability, kernel crashes, or denial of service affecting WiFi functionality on affected systems.

🟢

If Mitigated

Limited impact if exploit attempts fail or are detected by security controls, potentially causing only minor service disruption.

🌐 Internet-Facing: MEDIUM - Requires WiFi connectivity but could be exploited remotely if attacker can send malformed packets to vulnerable WiFi interfaces.

🏢 Internal Only: MEDIUM - Internal attackers with network access could exploit this vulnerability to compromise systems or cause denial of service.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ⚠️ Yes

Complexity: MEDIUM

Found during code review, not through active exploitation. Requires sending malformed WiFi packets to trigger the error condition and subsequent memory corruption.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Kernel versions containing the fix commits (7c0884fcd2ddde0544d2e77f297ae461e1f53f58 and related)

Vendor Advisory: https://git.kernel.org/stable/c/7c0884fcd2ddde0544d2e77f297ae461e1f53f58

Restart Required: Yes

Instructions:

1. Update Linux kernel to patched version. 2. Rebuild kernel if compiling from source. 3. Reboot system to load new kernel. 4. Verify ath12k driver is updated.

🔧 Temporary Workarounds

Disable ath12k driver

linux

Temporarily disable the vulnerable ath12k WiFi driver if not needed

modprobe -r ath12k
echo 'blacklist ath12k' >> /etc/modprobe.d/blacklist-ath12k.conf

Network segmentation

all

Isolate WiFi networks from critical systems to limit potential impact

🧯 If You Can't Patch

Implement strict network access controls to limit who can connect to WiFi networks
Monitor systems for kernel crashes or unusual WiFi driver behavior

🔍 How to Verify

Check if Vulnerable:

Check kernel version and verify if ath12k driver is loaded: 'lsmod | grep ath12k' and 'uname -r'

Check Version:

uname -r

Verify Fix Applied:

Verify kernel version is updated and check git commit history includes the fix commits

📡 Detection & Monitoring

Log Indicators:

Kernel panic messages
ath12k driver error logs
System crashes related to WiFi

Network Indicators:

Unusual WiFi packet patterns
Multiple connection attempts to trigger error conditions

SIEM Query:

source="kernel" AND ("ath12k" OR "kernel panic" OR "out of bounds")

📊 Metadata

CVE ID: CVE-2025-39761

CVSS v3 Score: 7.1 (HIGH)

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

CWE: CWE-125

EPSS Score: 0.01% exploit probability (1.2th percentile)

Published: September 11, 2025

Last Updated: November 26, 2025

🔗 References

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🔗 Related Vulnerabilities

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