CVE-2024-56631 – This is a use-after-free vulnerability in the L... (How to Fix)

Q: What is the severity of CVE-2024-56631?

CVE-2024-56631 has a CVSS score of 7.8 (HIGH). This is a use-after-free vulnerability in the Linux kernel's SCSI generic (sg) driver that allows local attackers to potentially crash the system or execute arbitrary code. It affects systems using the sg driver with local access, requiring an attacker to have user privileges to trigger the bug.

📋 TL;DR

This is a use-after-free vulnerability in the Linux kernel's SCSI generic (sg) driver that allows local attackers to potentially crash the system or execute arbitrary code. It affects systems using the sg driver with local access, requiring an attacker to have user privileges to trigger the bug.

💻 Affected Systems

Products:

Linux kernel

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

Operating Systems: Linux distributions using vulnerable kernel versions

Default Config Vulnerable: ⚠️ Yes

Notes: Only affects systems using the SCSI generic (sg) driver. Requires local user access to SCSI devices.

📦 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 →

⚠️ Risk & Real-World Impact

🔴

Worst Case

Local privilege escalation to kernel-level code execution, leading to complete system compromise.

🟠

Likely Case

Kernel panic or system crash causing denial of service.

🟢

If Mitigated

No impact if proper access controls prevent unauthorized local users from accessing SCSI devices.

🌐 Internet-Facing: LOW - Requires local access to exploit.

🏢 Internal Only: MEDIUM - Local users with access to SCSI devices could exploit this vulnerability.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ✅ No

Complexity: MEDIUM

Exploitation requires local access and knowledge of kernel memory layout. The bug was discovered through fuzzing (syzbot).

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Kernel versions containing commits: 198b89dd5a595ee3f96e5ce5c448b0484cd0e53c, 1f5e2f1ca5875728fcf62bc1a054707444ab4960, 275b8347e21ab8193e93223a8394a806e4ba8918, 285ce1f89f8d414e7eecab5ef5118cd512596318, or 59b30afa578637169e2819536bb66459fdddc39d

Vendor Advisory: https://git.kernel.org/stable/c/198b89dd5a595ee3f96e5ce5c448b0484cd0e53c

Restart Required: Yes

Instructions:

1. Update to a patched kernel version from your distribution's repositories. 2. Reboot the system to load the new kernel. 3. Verify the fix is applied by checking kernel version.

🔧 Temporary Workarounds

Disable SCSI generic driver

linux

Prevent loading of the vulnerable sg driver module

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

Restrict SCSI device access

linux

Limit access to SCSI devices to trusted users only

chmod 600 /dev/sg*
setfacl -m u:trusteduser:rw /dev/sg*

🧯 If You Can't Patch

Implement strict access controls to limit which users can access SCSI devices
Monitor system logs for kernel panics or unusual SCSI device access patterns

🔍 How to Verify

Check if Vulnerable:

Check kernel version and compare with distribution's security advisories. Run: uname -r

Check Version:

uname -r

Verify Fix Applied:

Verify kernel version is updated to a patched version. Check if sg module is loaded: lsmod | grep sg

📡 Detection & Monitoring

Log Indicators:

Kernel panic messages
KASAN error reports in dmesg
System crashes related to SCSI operations

Network Indicators:

None - local exploit only

SIEM Query:

source="kernel" AND ("KASAN" OR "slab-use-after-free" OR "sg_release")

📊 Metadata

CVE ID: CVE-2024-56631

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-416

Published: December 27, 2024

Last Updated: November 3, 2025

🔗 References

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🔗 Related Vulnerabilities

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