CVE-2019-15917 – This CVE describes a use-after-free vulnerabili... (How to Fix)

Q: What is the severity of CVE-2019-15917?

CVE-2019-15917 has a CVSS score of 7.0 (HIGH). This CVE describes a use-after-free vulnerability in the Linux kernel's Bluetooth HCI UART driver. When hci_uart_register_dev() fails during protocol setup, memory that has already been freed can be accessed, potentially leading to kernel crashes or arbitrary code execution. Systems running Linux kernels before version 5.0.5 with Bluetooth support are affected.

📋 TL;DR

This CVE describes a use-after-free vulnerability in the Linux kernel's Bluetooth HCI UART driver. When hci_uart_register_dev() fails during protocol setup, memory that has already been freed can be accessed, potentially leading to kernel crashes or arbitrary code execution. Systems running Linux kernels before version 5.0.5 with Bluetooth support are affected.

💻 Affected Systems

Products:

Linux kernel

Versions: All versions before 5.0.5

Operating Systems: Linux distributions using affected kernel versions

Default Config Vulnerable: ⚠️ Yes

Notes: Only affects systems with Bluetooth support enabled. The vulnerability is triggered during Bluetooth protocol setup failures.

📦 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 →

⚠️ Risk & Real-World Impact

🔴

Worst Case

Kernel panic leading to system crash, or potential privilege escalation to kernel-level code execution allowing full system compromise.

🟠

Likely Case

System instability, kernel crashes, or denial of service affecting Bluetooth functionality.

🟢

If Mitigated

Limited impact if Bluetooth is disabled or the vulnerable code path isn't triggered.

🌐 Internet-Facing: LOW - This requires local access or Bluetooth proximity to exploit.

🏢 Internal Only: MEDIUM - Attackers with local access or Bluetooth range could potentially exploit this vulnerability.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ✅ No

Complexity: HIGH

Exploitation requires triggering specific failure conditions in Bluetooth protocol setup, making reliable exploitation challenging.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Linux kernel 5.0.5 and later

Vendor Advisory: https://cdn.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.0.5

Restart Required: Yes

Instructions:

1. Update to Linux kernel 5.0.5 or later. 2. For distributions: Use package manager (apt/yum/dnf) to update kernel packages. 3. Reboot system to load new kernel.

🔧 Temporary Workarounds

Disable Bluetooth kernel module

linux

Prevent loading of vulnerable Bluetooth HCI UART driver

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

🧯 If You Can't Patch

Disable Bluetooth functionality at kernel level if not required
Implement strict access controls to limit local user privileges

🔍 How to Verify

Check if Vulnerable:

Check kernel version: uname -r. If version is earlier than 5.0.5, system is vulnerable.

Check Version:

uname -r

Verify Fix Applied:

After patching, verify kernel version is 5.0.5 or later with uname -r

📡 Detection & Monitoring

Log Indicators:

Kernel panic messages
Bluetooth subsystem crashes in dmesg
Use-after-free warnings in kernel logs

Network Indicators:

Unexpected Bluetooth service failures

SIEM Query:

source="kernel" AND ("use-after-free" OR "hci_uart" OR "Bluetooth crash")

📊 Metadata

CVE ID: CVE-2019-15917

CVSS v3 Score: 7.0 (HIGH)

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

CWE: CWE-416

Published: September 4, 2019

Last Updated: November 21, 2024

🔗 References

http://lists.opensuse.org/opensuse-security-announce/2019-09/msg00064.html Third Party Advisory
http://lists.opensuse.org/opensuse-security-announce/2019-09/msg00066.html Third Party Advisory
http://packetstormsecurity.com/files/155890/Slackware-Security-Advisory-Slackware-14.2-kernel-Updates.html Third Party Advisory,VDB Entry
https://cdn.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.0.5 Release Notes
https://github.com/torvalds/linux/commit/56897b217a1d0a91c9920cb418d6b3fe922f590a Patch
https://lists.debian.org/debian-lts-announce/2019/09/msg00025.html Third Party Advisory
https://lists.debian.org/debian-lts-announce/2020/03/msg00001.html Third Party Advisory
https://seclists.org/bugtraq/2020/Jan/10 Mailing List,Third Party Advisory
https://security.netapp.com/advisory/ntap-20191004-0001/ Third Party Advisory
http://lists.opensuse.org/opensuse-security-announce/2019-09/msg00064.html Third Party Advisory
http://lists.opensuse.org/opensuse-security-announce/2019-09/msg00066.html Third Party Advisory
http://packetstormsecurity.com/files/155890/Slackware-Security-Advisory-Slackware-14.2-kernel-Updates.html Third Party Advisory,VDB Entry
https://cdn.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.0.5 Release Notes
https://github.com/torvalds/linux/commit/56897b217a1d0a91c9920cb418d6b3fe922f590a Patch
https://lists.debian.org/debian-lts-announce/2019/09/msg00025.html Third Party Advisory
https://lists.debian.org/debian-lts-announce/2020/03/msg00001.html Third Party Advisory
https://seclists.org/bugtraq/2020/Jan/10 Mailing List,Third Party Advisory
https://security.netapp.com/advisory/ntap-20191004-0001/ Third Party Advisory

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💻 Affected Systems

📦 What is this software?

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⚠️ Risk & Real-World Impact

Worst Case

Likely Case

If Mitigated

🎯 Exploit Status

🛠️ Fix & Mitigation

✅ Official Fix

Instructions:

🔧 Temporary Workarounds

Disable Bluetooth kernel module

🧯 If You Can't Patch

🔍 How to Verify

Check if Vulnerable:

Check Version:

Verify Fix Applied:

📡 Detection & Monitoring

Log Indicators:

Network Indicators:

SIEM Query:

📊 Metadata

🔗 References

📤 Share & Export

🔗 Related Vulnerabilities