CVE-2024-40902 – This CVE describes a buffer overflow vulnerabil... (How to Fix)

Q: What is the severity of CVE-2024-40902?

CVE-2024-40902 has a CVSS score of 7.8 (HIGH). This CVE describes a buffer overflow vulnerability in the Linux kernel's JFS filesystem when handling invalid extended attributes (xattrs). An attacker could potentially exploit this to cause a kernel panic (denial of service) or possibly execute arbitrary code with kernel privileges. This affects Linux systems using the JFS filesystem.

📋 TL;DR

This CVE describes a buffer overflow vulnerability in the Linux kernel's JFS filesystem when handling invalid extended attributes (xattrs). An attacker could potentially exploit this to cause a kernel panic (denial of service) or possibly execute arbitrary code with kernel privileges. This affects Linux systems using the JFS filesystem.

💻 Affected Systems

Products:

Linux kernel with JFS filesystem support

Versions: Linux 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 in use. Many distributions don't enable JFS by default. Requires CONFIG_JFS_FS=y in kernel config.

📦 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 →

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 causing system crash and denial of service, requiring physical or remote console access to reboot.

🟢

If Mitigated

Minor system instability or logged warnings if exploit attempts are blocked by security controls.

🌐 Internet-Facing: LOW - Requires local filesystem access or ability to mount JFS partitions, not typically exposed directly to internet.

🏢 Internal Only: MEDIUM - Local users or compromised services with JFS access could exploit this to crash systems or potentially escalate privileges.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ✅ No

Complexity: MEDIUM

Requires local access to create/modify xattrs on JFS filesystem. Exploit would need to bypass kernel protections like KASLR and SMAP/SMEP.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Linux kernel with commits 1e84c9b1838152a87cf453270a5fa75c5037e83a or later

Vendor Advisory: https://git.kernel.org/stable/c/1e84c9b1838152a87cf453270a5fa75c5037e83a

Restart Required: Yes

Instructions:

1. Update Linux kernel to version containing the fix. 2. For distributions: Use package manager (apt/yum/dnf) to update kernel. 3. Reboot system to load new kernel.

🔧 Temporary Workarounds

Disable JFS filesystem

linux

Remove JFS kernel module to prevent use of vulnerable code path

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

Mount JFS partitions as noexec

linux

Prevent execution of potentially malicious code from JFS filesystem

mount -o remount,noexec /path/to/jfs/mountpoint

🧯 If You Can't Patch

Restrict local user access to systems with JFS filesystems
Implement strict access controls on JFS mount points and monitor for unusual xattr activity

🔍 How to Verify

Check if Vulnerable:

Check if JFS module is loaded: lsmod | grep jfs. Check kernel version against distribution security advisories.

Check Version:

uname -r

Verify Fix Applied:

Verify kernel version includes fix commits or is newer than vulnerable versions. Check /proc/version or uname -r.

📡 Detection & Monitoring

Log Indicators:

Kernel panic messages
JFS error messages in dmesg or /var/log/kern.log
Unexpected xattr operations on JFS filesystems

Network Indicators:

None - local vulnerability only

SIEM Query:

source="kernel" AND ("panic" OR "JFS" AND "xattr" AND "overflow")

📊 Metadata

CVE ID: CVE-2024-40902

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-120

Published: July 12, 2024

Last Updated: November 3, 2025

🔗 References

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🔗 Related Vulnerabilities

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