CVE-2022-49694 – This is a use-after-free vulnerability in the L... (How to Fix)

Q: What is the severity of CVE-2022-49694?

CVE-2022-49694 has a CVSS score of 7.8 (HIGH). This is a use-after-free vulnerability in the Linux kernel's block layer that occurs during disk removal operations. It allows local attackers with root privileges to potentially execute arbitrary code or cause denial of service by exploiting improper cleanup of elevator scheduler resources. Systems running vulnerable Linux kernel versions are affected.

📋 TL;DR

This is a use-after-free vulnerability in the Linux kernel's block layer that occurs during disk removal operations. It allows local attackers with root privileges to potentially execute arbitrary code or cause denial of service by exploiting improper cleanup of elevator scheduler resources. Systems running vulnerable Linux kernel versions are affected.

💻 Affected Systems

Products:

Linux kernel

Versions: Specific vulnerable versions not explicitly stated in CVE, but patches were committed to stable branches. Likely affects multiple kernel versions before the fix.

Operating Systems: Linux distributions using affected kernel versions

Default Config Vulnerable: ⚠️ Yes

Notes: Requires root privileges to trigger the vulnerable disk removal operation. Systems with frequent disk hotplug operations may be more exposed.

📦 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 →

⚠️ Risk & Real-World Impact

🔴

Worst Case

Local privilege escalation to kernel-level code execution leading to complete system compromise, data theft, or persistent backdoor installation.

🟠

Likely Case

Kernel panic or system crash causing denial of service, potentially requiring physical access or reboot to restore functionality.

🟢

If Mitigated

No impact if proper kernel hardening and privilege separation are implemented, as exploitation requires root privileges.

🌐 Internet-Facing: LOW - This is a local privilege escalation vulnerability requiring root access, not directly exploitable over network.

🏢 Internal Only: MEDIUM - Malicious insiders or compromised accounts with root access could exploit this to escalate privileges or cause system instability.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ✅ No

Complexity: MEDIUM

Exploitation requires root access and knowledge of kernel memory layout. No public exploits known as of analysis.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Patches available in stable kernel trees (commits 50e34d78815e474d410f342fbe783b18192ca518 and f28699fafc047ec33299da01e928c3a0073c5cc6)

Vendor Advisory: https://git.kernel.org/stable/c/50e34d78815e474d410f342fbe783b18192ca518

Restart Required: Yes

Instructions:

1. Update Linux kernel to patched version from distribution vendor. 2. Reboot system to load new kernel. 3. Verify kernel version after reboot.

🔧 Temporary Workarounds

Restrict root access

all

Limit root privileges to essential users and processes to reduce attack surface

Review sudoers configuration
Implement least privilege principles
Use capabilities instead of full root where possible

Disable unnecessary disk hotplug

all

Reduce exposure by minimizing disk removal operations

Disable automatic mounting of removable media
Configure storage to minimize hotplug events

🧯 If You Can't Patch

Implement strict access controls to prevent unauthorized root access
Monitor for suspicious disk removal operations and kernel panic events

🔍 How to Verify

Check if Vulnerable:

Check kernel version against distribution security advisories. Vulnerable if running unpatched kernel with commits before the fix.

Check Version:

uname -r

Verify Fix Applied:

Verify kernel version includes the fix commits: 50e34d78815e474d410f342fbe783b18192ca518 or f28699fafc047ec33299da01e928c3a0073c5cc6

📡 Detection & Monitoring

Log Indicators:

Kernel panic messages
OOPs (kernel crashes) related to block layer or elevator scheduler
Unexpected disk removal events in system logs

Network Indicators:

None - this is a local vulnerability

SIEM Query:

Search for: kernel panic, OOPs, use-after-free, block layer errors, or unexpected disk removal events in system logs

📊 Metadata

CVE ID: CVE-2022-49694

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

EPSS Score: 0.05% exploit probability (14.2th percentile)

Published: February 26, 2025

Last Updated: March 24, 2025

🔗 References

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