CVE-2024-44938 – This CVE-2024-44938 is a shift-out-of-bounds vu... (How to Fix)

Q: What is the severity of CVE-2024-44938?

CVE-2024-44938 has a CVSS score of 5.5 (MEDIUM). This CVE-2024-44938 is a shift-out-of-bounds vulnerability in the JFS filesystem driver in the Linux kernel. It allows local attackers to trigger a kernel panic (denial of service) by causing a negative shift operation when searching for block sizes. Systems using JFS filesystems with affected kernel versions are vulnerable.

📋 TL;DR

This CVE-2024-44938 is a shift-out-of-bounds vulnerability in the JFS filesystem driver in the Linux kernel. It allows local attackers to trigger a kernel panic (denial of service) by causing a negative shift operation when searching for block sizes. Systems using JFS filesystems with affected kernel versions are vulnerable.

💻 Affected Systems

Products:

Linux kernel with JFS filesystem support

Versions: Kernel versions before the fix commits (specific versions vary by distribution)

Operating Systems: Linux distributions with JFS support enabled

Default Config Vulnerable: ✅ No

Notes: Only vulnerable if JFS filesystem is actually mounted/used; many systems use ext4/xfs 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...

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 and denial of service, potentially causing data corruption or loss if filesystem operations are interrupted.

🟠

Likely Case

Local denial of service through kernel panic, requiring physical access or local user privileges to trigger.

🟢

If Mitigated

Minimal impact if JFS filesystems are not in use or if SELinux/AppArmor restricts access to JFS operations.

🌐 Internet-Facing: LOW - Requires local access to trigger; not remotely exploitable.

🏢 Internal Only: MEDIUM - Local users or compromised accounts could crash systems using JFS, affecting availability.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: NO

Unauthenticated Exploit: ✅ No

Complexity: MEDIUM

Requires local access and ability to trigger specific JFS operations; not trivial but documented in kernel commit.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Fixed in kernel commits: 234e6ea0855cdb5673d54ecaf7dc5c78f3e84630 and related backports

Vendor Advisory: https://git.kernel.org/stable/c/234e6ea0855cdb5673d54ecaf7dc5c78f3e84630

Restart Required: Yes

Instructions:

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

🔧 Temporary Workarounds

Disable JFS module

linux

Prevent loading of JFS kernel module if not needed

echo 'blacklist jfs' >> /etc/modprobe.d/blacklist-jfs.conf
rmmod jfs

Avoid JFS filesystems

linux

Do not mount or use JFS filesystems

# Check mounted filesystems: mount | grep jfs
# Unmount any JFS filesystems: umount /dev/jfs_device

🧯 If You Can't Patch

Restrict local user access to systems using JFS filesystems
Implement strict SELinux/AppArmor policies to limit JFS operations

🔍 How to Verify

Check if Vulnerable:

Check kernel version and if JFS is loaded: uname -r && lsmod | grep jfs

Check Version:

uname -r

Verify Fix Applied:

Verify kernel version is patched and check git commit history for the fix

📡 Detection & Monitoring

Log Indicators:

Kernel panic messages in /var/log/kern.log or dmesg
JFS-related error messages

Network Indicators:

None - local vulnerability only

SIEM Query:

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

📊 Metadata

CVE ID: CVE-2024-44938

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-787

Published: August 26, 2024

Last Updated: November 3, 2025

🔗 References

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🔗 Related Vulnerabilities

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