CVE-2023-26242 – This CVE describes an integer overflow vulnerab... (How to Fix)

Q: What is the severity of CVE-2023-26242?

CVE-2023-26242 has a CVSS score of 7.8 (HIGH). This CVE describes an integer overflow vulnerability in the Linux kernel's FPGA (Field Programmable Gate Array) driver component. Attackers could exploit this to cause a kernel crash (denial of service) or potentially execute arbitrary code with kernel privileges. Systems running affected Linux kernel versions with FPGA hardware or drivers loaded are vulnerable.

📋 TL;DR

This CVE describes an integer overflow vulnerability in the Linux kernel's FPGA (Field Programmable Gate Array) driver component. Attackers could exploit this to cause a kernel crash (denial of service) or potentially execute arbitrary code with kernel privileges. Systems running affected Linux kernel versions with FPGA hardware or drivers loaded are vulnerable.

💻 Affected Systems

Products:

Linux kernel

Versions: Through 6.1.12

Operating Systems: Linux distributions using vulnerable kernel versions

Default Config Vulnerable: ✅ No

Notes: Only vulnerable if FPGA (DFL-AFU) drivers are loaded and FPGA hardware is present/accessible. Most standard Linux installations are not affected unless specifically using FPGA acceleration.

📦 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...

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⚠️ Risk & Real-World Impact

🔴

Worst Case

Kernel memory corruption leading to arbitrary code execution with kernel privileges, potentially resulting in full system compromise.

🟠

Likely Case

Kernel panic or denial of service causing system instability or crashes.

🟢

If Mitigated

Limited impact if FPGA drivers are not loaded or hardware is not present; system remains stable.

🌐 Internet-Facing: LOW - Requires local access or ability to load kernel modules; not directly exploitable over network.

🏢 Internal Only: MEDIUM - Local attackers or malicious insiders could exploit if they have sufficient privileges to interact with FPGA devices.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ✅ No

Complexity: MEDIUM

Exploitation requires local access and ability to interact with FPGA device interfaces. No public exploit code has been disclosed as of available references.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Linux kernel 6.1.13 and later, or backported patches for stable branches

Vendor Advisory: https://patchwork.kernel.org/project/linux-fpga/patch/20230206054326.89323-1-k1rh4.lee%40gmail.com

Restart Required: Yes

Instructions:

1. Update Linux kernel to version 6.1.13 or later. 2. For distributions with backports, apply security patches from your vendor. 3. Reboot system to load patched kernel.

🔧 Temporary Workarounds

Disable FPGA drivers

linux

Prevent loading of vulnerable FPGA drivers if FPGA hardware is not required

echo 'blacklist dfl-afu' >> /etc/modprobe.d/blacklist.conf
rmmod dfl_afu

Restrict device access

linux

Limit access to FPGA device files to prevent unauthorized users from triggering the vulnerability

chmod 600 /dev/dfl-afu*
chown root:root /dev/dfl-afu*

🧯 If You Can't Patch

Implement strict access controls to prevent unauthorized users from accessing FPGA device interfaces (/dev/dfl-afu*)
Monitor system logs for unusual FPGA driver activity or kernel panic events

🔍 How to Verify

Check if Vulnerable:

Check kernel version: uname -r. If version is 6.1.12 or earlier, check if dfl_afu module is loaded: lsmod | grep dfl_afu

Check Version:

uname -r

Verify Fix Applied:

Verify kernel version is 6.1.13 or later: uname -r. Confirm dfl_afu module version if loaded.

📡 Detection & Monitoring

Log Indicators:

Kernel panic messages related to FPGA drivers
OOM (Out of Memory) errors from kernel
System crashes or unexpected reboots

Network Indicators:

None - local vulnerability only

SIEM Query:

source="kernel" AND ("panic" OR "Oops" OR "BUG") AND ("dfl" OR "afu" OR "fpga")

📊 Metadata

CVE ID: CVE-2023-26242

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-190

Published: February 21, 2023

Last Updated: May 5, 2025

🔗 References

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