CVE-2022-49708

5.5 MEDIUM

Denial of Service

📋 TL;DR

This vulnerability in the Linux kernel's ext4 filesystem can trigger a kernel panic (system crash) when specific conditions cause a BUG_ON assertion failure during disk space allocation. It affects Linux systems using ext4 filesystem with specific configurations. The vulnerability requires local access to trigger.

💻 Affected Systems

Products:

Linux kernel

Versions: Specific kernel versions with vulnerable ext4 code (check git commits for exact ranges)

Operating Systems: Linux distributions using affected kernel versions

Default Config Vulnerable: ⚠️ Yes

Notes: Requires ext4 filesystem with specific block/group configurations. The vulnerability triggers when using fallocate and fsstress with specific parameters on ext4 filesystems with block size 1024 and group size 256.

📦 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 →

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 →

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

Complete system crash and denial of service, potentially causing data corruption or loss if the crash occurs during critical filesystem operations.

🟠

Likely Case

Local denial of service through system crash when specific filesystem operations are performed on specially configured ext4 filesystems.

🟢

If Mitigated

No impact if patched or if the specific triggering conditions are avoided.

🌐 Internet-Facing: LOW - Requires local filesystem access to trigger, not directly exploitable over network.

🏢 Internal Only: MEDIUM - Local users or processes with filesystem access could crash the system, affecting availability.

🎯 Exploit Status

Public PoC: ⚠️ Yes

Weaponized: LIKELY

Unauthenticated Exploit: ✅ No

Complexity: LOW

Reproduction commands are provided in the CVE description. Exploitation requires local access and knowledge of specific filesystem parameters.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Kernel versions with commits: 5707d721d1819db57dba57b1d4623034fcb32047, 6880fb2e64331b9fdc85d3f32b1d7e81ad8703f1, 6fdaf31ad5f3d3afab744dfd9a8b0d9142aa881f, 887a3e9ad4b8309a2266bce7ae749b2bf1f7a687, 90f0f9d45dff0128c0fca0d2358c4153b024afa6

Vendor Advisory: https://git.kernel.org/stable/c/5707d721d1819db57dba57b1d4623034fcb32047

Restart Required: Yes

Instructions:

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

🔧 Temporary Workarounds

Avoid triggering conditions

linux

Avoid using fallocate with specific parameters on ext4 filesystems with block size 1024 and group size 256

🧯 If You Can't Patch

Restrict local user access to systems with vulnerable configurations
Monitor for crash logs and investigate any kernel panics related to ext4_mb_mark_diskspace_used

🔍 How to Verify

Check if Vulnerable:

Check kernel version and compare with patched versions. Test with reproduction commands: fallocate -l100M disk; mkfs.ext4 -b 1024 -g 256 disk; mount disk /mnt; fsstress -d /mnt -l 0 -n 1000 -p 1

Check Version:

uname -r

Verify Fix Applied:

After patching, attempt reproduction commands - system should not crash. Check kernel logs for absence of BUG_ON messages related to ext4_mb_mark_diskspace_used.

📡 Detection & Monitoring

Log Indicators:

Kernel panic messages containing 'ext4_mb_mark_diskspace_used'
BUG_ON messages in kernel logs
System crash/reboot events

SIEM Query:

source="kernel" AND ("ext4_mb_mark_diskspace_used" OR "BUG_ON" OR "kernel panic")

📊 Metadata

CVE ID: CVE-2022-49708

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-617

EPSS Score: 0.03% exploit probability (8.3th percentile)

Published: February 26, 2025

Last Updated: October 24, 2025

🔗 References