CVE-2025-39735 – This CVE describes an integer overflow vulnerab... (How to Fix)

Q: What is the severity of CVE-2025-39735?

CVE-2025-39735 has a CVSS score of 7.1 (HIGH). This CVE describes an integer overflow vulnerability in the Linux kernel's JFS filesystem extended attribute handling. When processing specially crafted extended attributes, an out-of-bounds read can occur, potentially leading to information disclosure or system instability. Systems using JFS filesystems with the affected Linux kernel versions are vulnerable.

📋 TL;DR

This CVE describes an integer overflow vulnerability in the Linux kernel's JFS filesystem extended attribute handling. When processing specially crafted extended attributes, an out-of-bounds read can occur, potentially leading to information disclosure or system instability. Systems using JFS filesystems with the affected Linux kernel versions are vulnerable.

💻 Affected Systems

Products:

Linux kernel

Versions: Specific affected versions not explicitly stated; check kernel commit history for exact range

Operating Systems: Linux distributions using vulnerable kernel versions

Default Config Vulnerable: ⚠️ Yes

Notes: Only affects systems using JFS filesystems; vulnerability is in kernel code, not user-space applications

📦 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 disclosure leading to information leakage, potential privilege escalation if combined with other vulnerabilities, or kernel panic causing system crash.

🟠

Likely Case

Information disclosure from kernel memory, system instability, or denial of service through kernel panic.

🟢

If Mitigated

Limited impact if JFS filesystems are not in use or if access controls prevent malicious file uploads.

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

🏢 Internal Only: MEDIUM - Local users or processes with filesystem access could trigger the vulnerability.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ✅ No

Complexity: MEDIUM

Requires ability to create or modify files on JFS filesystem; local access needed

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Kernel versions containing commits: 0beddc2a3f9b9cf7d8887973041e36c2d0fa3652, 16d3d36436492aa248b2d8045e75585ebcc2f34d, 3d6fd5b9c6acbc005e53d0211c7381f566babec1, 46e2c031aa59ea65128991cbca474bd5c0c2ecdb, 50afcee7011155933d8d5e8832f52eeee018cfd3

Vendor Advisory: https://git.kernel.org/stable/c/0beddc2a3f9b9cf7d8887973041e36c2d0fa3652

Restart Required: Yes

Instructions:

Update Linux kernel to patched version
Reboot system after kernel update
Verify kernel version after reboot

🔧 Temporary Workarounds

Disable JFS filesystem use

linux

Avoid using JFS filesystems until patched

# Check for JFS filesystems: mount | grep -i jfs
# Unmount JFS filesystems if possible: umount /path/to/jfs/mountpoint

Restrict filesystem access

linux

Limit who can create/modify files on JFS filesystems

# Set restrictive permissions: chmod 700 /jfs/mountpoint
# Use access control lists if needed

🧯 If You Can't Patch

Avoid using JFS filesystems for untrusted data
Implement strict file upload controls and validation for JFS-mounted directories

🔍 How to Verify

Check if Vulnerable:

Check kernel version and verify if JFS filesystems are mounted: uname -r && mount | grep jfs

Check Version:

uname -r

Verify Fix Applied:

Verify kernel version is updated and contains the fix commits: uname -r && zgrep -i 'ea_get\|CVE-2025-39735' /proc/config.gz

📡 Detection & Monitoring

Log Indicators:

Kernel logs showing 'ea_get: invalid extended attribute'
Kernel panic or oops messages related to JFS or slab corruption

Network Indicators:

No network indicators - local filesystem vulnerability

SIEM Query:

source="kernel" AND ("ea_get" OR "JFS" OR "slab-out-of-bounds")

📊 Metadata

CVE ID: CVE-2025-39735

CVSS v3 Score: 7.1 (HIGH)

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

CWE: CWE-125

EPSS Score: 0.07% exploit probability (21.6th percentile)

Published: April 18, 2025

Last Updated: November 3, 2025

🔗 References

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