CVE-2024-56663 – This is an off-by-one vulnerability in the Linu... (How to Fix)

Q: What is the severity of CVE-2024-56663?

CVE-2024-56663 has a CVSS score of 7.1 (HIGH). This is an off-by-one vulnerability in the Linux kernel's nl80211 WiFi subsystem that allows out-of-bounds memory access when handling Multi-Link Operation (MLO) link IDs. Attackers with local access can trigger a kernel crash (DoS) or potentially execute arbitrary code. Systems running vulnerable Linux kernel versions with WiFi capabilities are affected.

📋 TL;DR

This is an off-by-one vulnerability in the Linux kernel's nl80211 WiFi subsystem that allows out-of-bounds memory access when handling Multi-Link Operation (MLO) link IDs. Attackers with local access can trigger a kernel crash (DoS) or potentially execute arbitrary code. Systems running vulnerable Linux kernel versions with WiFi capabilities are affected.

💻 Affected Systems

Products:

Linux kernel

Versions: Kernel versions with MLO support up to the fix (specific versions in git commits)

Operating Systems: Linux distributions using vulnerable kernel versions

Default Config Vulnerable: ⚠️ Yes

Notes: Requires WiFi interface with MLO capability enabled. Most modern WiFi 6E/7 hardware supports MLO.

📦 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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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 arbitrary code execution with kernel privileges, potentially resulting in full system compromise.

🟠

Likely Case

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

🟢

If Mitigated

Limited impact if WiFi is disabled or MLO features are not used.

🌐 Internet-Facing: LOW - Requires local access or network proximity to WiFi interface.

🏢 Internal Only: MEDIUM - Local attackers or compromised users can exploit this vulnerability.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ✅ No

Complexity: MEDIUM

Requires CAP_NET_ADMIN or root privileges to send nl80211 commands. The crash stack shows it was found by fuzzing.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Patched in kernel commits: 29e640ae641b9f5ffc666049426d2b16c98d9963, 2e3dbf938656986cce73ac4083500d0bcfbffe24, f3412522f78826fef1dfae40ef378a863df2591c, f850d1d9f1106f528dfc5807565f2d1fa9a397d3

Vendor Advisory: https://lists.debian.org/debian-lts-announce/2025/03/msg00001.html

Restart Required: Yes

Instructions:

1. Update Linux kernel to patched version from your distribution. 2. For Debian: apt update && apt upgrade linux-image-*. 3. Reboot system to load new kernel.

🔧 Temporary Workarounds

Disable WiFi MLO

linux

Disable Multi-Link Operation features if not required

iw dev wlan0 set mlo disabled

Restrict nl80211 access

linux

Limit CAP_NET_ADMIN capabilities to prevent unprivileged users from sending nl80211 commands

setcap -r /usr/sbin/iw

🧯 If You Can't Patch

Disable WiFi interfaces completely if not needed
Implement strict access controls to prevent unprivileged users from accessing WiFi configuration

🔍 How to Verify

Check if Vulnerable:

Check kernel version and if MLO is enabled: uname -r && iw phy | grep -i mlo

Check Version:

uname -r

Verify Fix Applied:

Verify kernel version is updated beyond vulnerable commits and test WiFi MLO functionality

📡 Detection & Monitoring

Log Indicators:

Kernel panic messages
KASAN reports of wild-memory-access in nl80211 or ieee80211 modules
System crashes/reboots

Network Indicators:

Abnormal nl80211 netlink traffic patterns
Multiple control port transmission attempts

SIEM Query:

source="kernel" AND ("KASAN" OR "wild-memory-access" OR "nl80211" OR "ieee80211_tx_control_port")

📊 Metadata

CVE ID: CVE-2024-56663

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-193

Published: December 27, 2024

Last Updated: November 3, 2025

🔗 References

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