CVE-2024-26884 – A vulnerability in the Linux kernel's BPF subsy... (How to Fix)

Q: What is the severity of CVE-2024-26884?

CVE-2024-26884 has a CVSS score of 7.8 (HIGH). A vulnerability in the Linux kernel's BPF subsystem allows integer overflow during hashtable bucket calculation on 32-bit architectures. This can lead to undefined behavior, potentially causing kernel crashes or local privilege escalation. Systems running 32-bit Linux kernels with BPF enabled are affected.

📋 TL;DR

A vulnerability in the Linux kernel's BPF subsystem allows integer overflow during hashtable bucket calculation on 32-bit architectures. This can lead to undefined behavior, potentially causing kernel crashes or local privilege escalation. Systems running 32-bit Linux kernels with BPF enabled are affected.

💻 Affected Systems

Products:

Linux kernel

Versions: Specific affected versions not explicitly stated in CVE, but the fix commits indicate it affects multiple stable branches. Likely affects kernel versions with the vulnerable BPF hashtab code.

Operating Systems: Linux distributions using affected kernel versions

Default Config Vulnerable: ⚠️ Yes

Notes: Only affects 32-bit architectures (i386, arm, etc.). Requires BPF functionality to be enabled and used.

📦 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 →

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

Local privilege escalation to root, kernel panic leading to denial of service, or arbitrary code execution in kernel context.

🟠

Likely Case

Kernel crash/panic causing system instability or denial of service when specific BPF programs trigger the overflow condition.

🟢

If Mitigated

Minimal impact if BPF is disabled or systems use 64-bit architectures where the overflow doesn't occur.

🌐 Internet-Facing: LOW - This is a local vulnerability requiring local access to trigger.

🏢 Internal Only: MEDIUM - Internal users with shell access could potentially exploit this for privilege escalation or DoS attacks.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ✅ No

Complexity: MEDIUM

Exploitation requires local access and ability to load BPF programs. Triggered by syzbot fuzzing, suggesting reliable triggering is possible.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Fixed in kernel commits: 33ec04cadb77605b71d9298311919303d390c4d5, 3b08cfc65f07b1132c1979d73f014ae6e04de55d, 64f00b4df0597590b199b62a37a165473bf658a6, 6787d916c2cf9850c97a0a3f73e08c43e7d973b1, 8435f0961bf3dc65e204094349bd9aeaac1f8868

Vendor Advisory: https://git.kernel.org/stable/c/33ec04cadb77605b71d9298311919303d390c4d5

Restart Required: Yes

Instructions:

1. Update Linux kernel to version containing the fix commits. 2. Check your distribution's security advisories for patched kernel packages. 3. Reboot system after kernel update.

🔧 Temporary Workarounds

Disable BPF subsystem

linux

Disable BPF functionality to prevent exploitation

echo 1 > /proc/sys/kernel/unprivileged_bpf_disabled
Remove BPF kernel modules if possible

Restrict BPF usage

linux

Limit BPF program loading to privileged users only

sysctl -w kernel.unprivileged_bpf_disabled=1

🧯 If You Can't Patch

Migrate 32-bit systems to 64-bit architecture where possible
Implement strict access controls to prevent unprivileged users from loading BPF programs

🔍 How to Verify

Check if Vulnerable:

Check kernel version and architecture: 'uname -r' and 'uname -m'. If 32-bit (i686, i386, arm, etc.) and using a kernel version before the fix commits, system may be vulnerable.

Check Version:

uname -r

Verify Fix Applied:

Verify kernel version includes the fix commits: 'grep -q "33ec04cadb77605b71d9298311919303d390c4d5" /proc/version' or check with distribution package manager.

📡 Detection & Monitoring

Log Indicators:

Kernel panic logs
BPF program loading failures
System crash/reboot events

Network Indicators:

None - local vulnerability only

SIEM Query:

source="kernel" AND ("panic" OR "Oops" OR "BPF")

📊 Metadata

CVE ID: CVE-2024-26884

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-119

Published: April 17, 2024

Last Updated: November 21, 2024

🔗 References

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🔗 Related Vulnerabilities

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