CVE-2022-49956 – This CVE describes a use-after-free vulnerabili... (How to Fix)

Q: What is the severity of CVE-2022-49956?

CVE-2022-49956 has a CVSS score of 7.8 (HIGH). This CVE describes a use-after-free vulnerability in the Linux kernel's rtl8712 staging driver. When Read/Write_MACREG callbacks are NULL, the read/write_macreg_hdl() functions free the 'pcmd' pointer without proper validation, leading to potential memory corruption. This affects Linux systems using the vulnerable rtl8712 driver.

📋 TL;DR

This CVE describes a use-after-free vulnerability in the Linux kernel's rtl8712 staging driver. When Read/Write_MACREG callbacks are NULL, the read/write_macreg_hdl() functions free the 'pcmd' pointer without proper validation, leading to potential memory corruption. This affects Linux systems using the vulnerable rtl8712 driver.

💻 Affected Systems

Products:

Linux kernel with rtl8712 staging driver

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

Operating Systems: Linux

Default Config Vulnerable: ✅ No

Notes: Only vulnerable if the rtl8712 staging driver is loaded and in use. This is a Realtek WiFi driver often used for specific wireless chipsets.

📦 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 panic, system crash, or potential local privilege escalation allowing attackers to execute arbitrary code with kernel privileges.

🟠

Likely Case

System instability, crashes, or denial of service affecting the network functionality of systems using the rtl8712 driver.

🟢

If Mitigated

Limited impact with proper kernel hardening and driver isolation, potentially just driver malfunction without system-wide effects.

🌐 Internet-Facing: LOW - This is a local kernel driver vulnerability requiring local access or adjacent network position to exploit.

🏢 Internal Only: MEDIUM - Internal attackers with local access could potentially exploit this to cause system instability or attempt privilege escalation.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ✅ No

Complexity: MEDIUM

Exploitation requires local access and specific conditions where the vulnerable driver functions are triggered. No public exploits have been documented.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Fixed in Linux kernel stable releases via the referenced git commits

Vendor Advisory: https://git.kernel.org/stable/c/19e3f69d19801940abc2ac37c169882769ed9770

Restart Required: Yes

Instructions:

1. Update Linux kernel to a version containing the fix commits. 2. For distributions: Use package manager to update kernel package. 3. Reboot system to load patched kernel.

🔧 Temporary Workarounds

Disable rtl8712 driver

linux

Prevent loading of the vulnerable driver module

echo 'blacklist r8712u' >> /etc/modprobe.d/blacklist.conf
rmmod r8712u

🧯 If You Can't Patch

Disable or blacklist the rtl8712 driver module
Implement strict access controls to limit local user access to systems using this driver

🔍 How to Verify

Check if Vulnerable:

Check if rtl8712 driver is loaded: lsmod | grep r8712u

Check Version:

uname -r

Verify Fix Applied:

Check kernel version against patched versions from distribution vendor, and verify driver is not loaded or updated

📡 Detection & Monitoring

Log Indicators:

Kernel oops messages
System crash logs
Driver-related error messages in dmesg

Network Indicators:

Unusual network interface behavior
WiFi connectivity issues on affected hardware

SIEM Query:

source="kernel" AND ("r8712u" OR "rtl8712" OR "use-after-free")

📊 Metadata

CVE ID: CVE-2022-49956

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: 0.02% exploit probability (3.7th percentile)

Published: June 18, 2025

Last Updated: November 17, 2025

🔗 References

📤 Share & Export

📄 Export Markdown 📋 Export JSON

🔗 Related Vulnerabilities

If you're affected by CVE-2022-49956, you might also want to check these: