CVE-2024-49882 – A double-free vulnerability in the Linux kernel... (How to Fix)

Q: What is the severity of CVE-2024-49882?

CVE-2024-49882 has a CVSS score of 7.8 (HIGH). A double-free vulnerability in the Linux kernel's ext4 filesystem driver allows an attacker to cause a kernel panic or potentially achieve privilege escalation. This affects systems running vulnerable Linux kernel versions with ext4 filesystems. The vulnerability occurs when handling extent tree operations under specific error conditions.

📋 TL;DR

A double-free vulnerability in the Linux kernel's ext4 filesystem driver allows an attacker to cause a kernel panic or potentially achieve privilege escalation. This affects systems running vulnerable Linux kernel versions with ext4 filesystems. The vulnerability occurs when handling extent tree operations under specific error conditions.

💻 Affected Systems

Products:

Linux kernel

Versions: Specific vulnerable versions not explicitly stated, but references indicate fixes in stable kernel trees. Likely affects multiple 6.x kernel versions.

Operating Systems: Linux distributions using vulnerable kernel versions

Default Config Vulnerable: ⚠️ Yes

Notes: Requires ext4 filesystem usage. The vulnerability is triggered during specific extent tree operations under error conditions.

📦 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 →

⚠️ Risk & Real-World Impact

🔴

Worst Case

Kernel panic leading to denial of service, or potential privilege escalation if combined with other vulnerabilities to achieve arbitrary code execution.

🟠

Likely Case

Kernel panic causing system crash and denial of service when specific filesystem operations trigger the double-free condition.

🟢

If Mitigated

System remains stable with no impact if patched or if the specific error path isn't triggered.

🌐 Internet-Facing: LOW - Requires local access or ability to trigger specific filesystem operations.

🏢 Internal Only: MEDIUM - Local users or processes could trigger the vulnerability, potentially causing system instability.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ✅ No

Complexity: HIGH - Requires triggering specific error paths in ext4 extent handling.

Exploitation requires local access and ability to perform filesystem operations that trigger the specific error condition.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Patched in stable kernel commits: 230ee0535d01478bad9a3037292043f39b9be10b, 32bbb59e3f18facd7201bef110010bf35819b8c3, 68a69cf60660c73990c1875f94a5551600b04775, 7633407ca4ab8be2916ab214eb44ccebc6a50e1a, 78bbc3d15b6f443acb26e94418c445bac940d414

Vendor Advisory: https://git.kernel.org/stable/c/230ee0535d01478bad9a3037292043f39b9be10b

Restart Required: Yes

Instructions:

1. Update Linux kernel to version containing the fix. 2. Check with your distribution for specific kernel updates. 3. Reboot system after kernel update.

🔧 Temporary Workarounds

Avoid ext4 filesystem operations

linux

Limit filesystem operations that could trigger the extent tree error path

🧯 If You Can't Patch

Monitor system logs for kernel warnings related to buffer handling
Implement strict access controls to limit who can perform filesystem operations

🔍 How to Verify

Check if Vulnerable:

Check kernel version and compare with patched versions. Look for kernel warnings about 'brelse: Trying to free free buffer' in dmesg.

Check Version:

uname -r

Verify Fix Applied:

Verify kernel version includes one of the fix commits. Check that the warning no longer appears during filesystem operations.

📡 Detection & Monitoring

Log Indicators:

VFS: brelse: Trying to free free buffer
WARNING at fs/buffer.c:1241 __brelse
Kernel panic messages

Network Indicators:

None - local vulnerability

SIEM Query:

source="kernel" AND "brelse: Trying to free free buffer"

📊 Metadata

CVE ID: CVE-2024-49882

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-415

Published: October 21, 2024

Last Updated: November 3, 2025

🔗 References

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🔗 Related Vulnerabilities

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