CVE-2024-56648 – This vulnerability in the Linux kernel's HSR (H... (How to Fix)

Q: What is the severity of CVE-2024-56648?

CVE-2024-56648 has a CVSS score of 5.5 (MEDIUM). This vulnerability in the Linux kernel's HSR (High-availability Seamless Redundancy) protocol implementation allows an attacker to trigger an out-of-bounds memory access by sending specially crafted packets. This could lead to kernel memory corruption, crashes, or potential privilege escalation. Systems using HSR networking with vulnerable kernel versions are affected.

📋 TL;DR

This vulnerability in the Linux kernel's HSR (High-availability Seamless Redundancy) protocol implementation allows an attacker to trigger an out-of-bounds memory access by sending specially crafted packets. This could lead to kernel memory corruption, crashes, or potential privilege escalation. Systems using HSR networking with vulnerable kernel versions are affected.

💻 Affected Systems

Products:

Linux kernel

Versions: Specific affected versions not explicitly stated in CVE, but patches exist for stable branches. Likely affects multiple kernel versions before the fix.

Operating Systems: Linux distributions using vulnerable kernel versions

Default Config Vulnerable: ✅ No

Notes: Only vulnerable if HSR protocol is enabled and configured. Most systems don't use HSR 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...

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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 panic leading to system crash, potential privilege escalation to kernel mode, or remote code execution.

🟠

Likely Case

System instability, kernel crashes (denial of service), or information disclosure from uninitialized kernel memory.

🟢

If Mitigated

Minimal impact if HSR is not used or proper network segmentation isolates HSR traffic.

🌐 Internet-Facing: LOW - HSR is typically used in industrial/embedded networks, not directly internet-facing.

🏢 Internal Only: MEDIUM - Internal attackers on the same network segment could exploit this if HSR is enabled.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ⚠️ Yes

Complexity: MEDIUM

Exploitation requires sending specially crafted packets to HSR interfaces. Discovered via syzbot fuzzing.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Patches available in stable kernel branches (commits: 3c215663b3e27a3b08cefcaea623ff54c70c8035, 6bb5c8ebc99f0671dbd3c9408ebaf935c3951186, 7ea527fbd7b94d0bee64a0a7e98279bcc654b322, aa632691c722a123e47ccd05a3afdd5f87a36061, b9653d19e556c6afd035602927a93d100a0d7644)

Vendor Advisory: https://git.kernel.org/stable/c/3c215663b3e27a3b08cefcaea623ff54c70c8035

Restart Required: Yes

Instructions:

1. Update Linux kernel to patched version from your distribution. 2. Reboot system to load new kernel. 3. Verify kernel version after reboot.

🔧 Temporary Workarounds

Disable HSR module

linux

Prevent loading of HSR kernel module if not needed

echo 'install hsr /bin/false' >> /etc/modprobe.d/disable-hsr.conf
rmmod hsr

Network segmentation

all

Isolate HSR network traffic to trusted segments only

🧯 If You Can't Patch

Disable HSR protocol if not required for operations
Implement strict network ACLs to limit access to HSR interfaces

🔍 How to Verify

Check if Vulnerable:

Check if HSR module is loaded: lsmod | grep hsr. If loaded and kernel version is unpatched, system is vulnerable.

Check Version:

uname -r

Verify Fix Applied:

Check kernel version includes one of the fix commits: uname -r. Verify HSR module functions normally after patch.

📡 Detection & Monitoring

Log Indicators:

Kernel panic logs
HSR protocol errors in dmesg
System crashes

Network Indicators:

Unusual packets to HSR ports
Malformed VLAN-tagged packets on HSR interfaces

SIEM Query:

source="kernel" AND ("HSR" OR "hsr_forward" OR "fill_frame_info") AND ("panic" OR "BUG" OR "oops")

📊 Metadata

CVE ID: CVE-2024-56648

CVSS v3 Score: 5.5 (MEDIUM)

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

CWE: CWE-908

Published: December 27, 2024

Last Updated: November 3, 2025

🔗 References

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