CVE-2021-47529
📋 TL;DR
This CVE describes a memory leak vulnerability in the iwlwifi driver of the Linux kernel. When specific error conditions occur during wireless operations, allocated memory isn't properly freed, leading to resource exhaustion. This affects systems using Intel wireless hardware with vulnerable kernel versions.
💻 Affected Systems
- Linux kernel iwlwifi driver
📦 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 →⚠️ Risk & Real-World Impact
Worst Case
Sustained exploitation could cause kernel memory exhaustion, leading to system instability, crashes, or denial of service on affected systems.
Likely Case
Gradual memory consumption over time causing performance degradation or eventual system instability requiring reboot.
If Mitigated
Minimal impact with proper monitoring and memory limits in place; may cause occasional performance issues.
🎯 Exploit Status
Exploitation requires triggering specific error conditions in wireless operations; no known public exploits.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Kernel versions containing commits 4768935c25403ba96e7a745645df24a51a774b7e and a571bc28326d9f3e13f5f2d9cda2883e0631b0ce
Vendor Advisory: https://git.kernel.org/stable/c/4768935c25403ba96e7a745645df24a51a774b7e
Restart Required: Yes
Instructions:
1. Update Linux kernel to patched version. 2. Reboot system. 3. Verify kernel version and driver functionality.
🔧 Temporary Workarounds
Disable affected wireless interface
linuxTemporarily disable Intel wireless interface to prevent vulnerability trigger
sudo ip link set wlan0 down
sudo rfkill block wifi
Use alternative wireless driver
linuxSwitch to different wireless driver if available for hardware
sudo modprobe -r iwlwifi
sudo modprobe alternative_driver
🧯 If You Can't Patch
- Implement memory monitoring and alerting for kernel memory usage
- Schedule regular system reboots to clear accumulated memory leaks
🔍 How to Verify
Check if Vulnerable:
Check kernel version and verify if iwlwifi module is loaded: lsmod | grep iwlwifiCheck Version:
uname -rVerify Fix Applied:
Verify kernel version includes fix commits and test wireless functionality📡 Detection & Monitoring
Log Indicators:
- Kernel oom-killer messages
- Increasing memory usage in /proc/meminfo
- iwlwifi driver error messages in dmesg
Network Indicators:
- Wireless connectivity issues on affected systems
SIEM Query:
source="kernel" AND ("oom" OR "out of memory") AND "iwlwifi"