CVE-2021-47633
📋 TL;DR
This is an out-of-bounds write vulnerability in the Linux kernel's ath5k wireless driver. It allows attackers with local access to potentially crash the system or execute arbitrary code. Systems using affected Linux kernel versions with the ath5k driver loaded are vulnerable.
💻 Affected Systems
- Linux kernel
📦 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 →⚠️ Risk & Real-World Impact
Worst Case
Local privilege escalation to kernel-level code execution, potentially leading to full system compromise.
Likely Case
Kernel panic or system crash causing denial of service.
If Mitigated
No impact if kernel is patched or ath5k module is not loaded.
🎯 Exploit Status
Exploitation requires local access and knowledge of kernel memory layout. The vulnerability was discovered through fuzzing.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Kernel versions containing the fix commits (25efc5d03455c3839249bc77fce5e29ecb54677e and related)
Vendor Advisory: https://git.kernel.org/stable/c/25efc5d03455c3839249bc77fce5e29ecb54677e
Restart Required: No
Instructions:
1. Update Linux kernel to patched version from your distribution. 2. Rebuild kernel if compiling from source. 3. Load new kernel module if using module.
🔧 Temporary Workarounds
Disable ath5k module
allPrevent loading of vulnerable ath5k driver module
echo 'blacklist ath5k' >> /etc/modprobe.d/blacklist-ath5k.conf
rmmod ath5k
🧯 If You Can't Patch
- Restrict local user access to systems with vulnerable kernels
- Implement strict access controls and monitoring for kernel module loading
🔍 How to Verify
Check if Vulnerable:
Check kernel version and if ath5k module is loaded: 'uname -r' and 'lsmod | grep ath5k'Check Version:
uname -rVerify Fix Applied:
Verify kernel version is patched and check for presence of fix commits in kernel source📡 Detection & Monitoring
Log Indicators:
- Kernel panic messages
- OOB write errors in kernel logs
- ath5k module crash reports
Network Indicators:
- None - local exploit only
SIEM Query:
kernel:panic OR kernel:oob OR kernel:ath5k🔗 References
- https://git.kernel.org/stable/c/25efc5d03455c3839249bc77fce5e29ecb54677e
- https://git.kernel.org/stable/c/564d4eceb97eaf381dd6ef6470b06377bb50c95a
- https://git.kernel.org/stable/c/9d7d83d0399e23d66fd431b553842a84ac10398f
- https://git.kernel.org/stable/c/be2f81024e7981565d90a4c9ca3067d11b6bca7f
- https://git.kernel.org/stable/c/c4e2f577271e158d87a916afb4e87415a88ce856
- https://git.kernel.org/stable/c/cbd96d6cad6625feba9c8d101ed4977d53e82f8e
- https://git.kernel.org/stable/c/ed3dfdaa8b5f0579eabfc1c5818eed30cfe1fe84
- https://git.kernel.org/stable/c/f4de974019a0adf34d0e7de6b86252f1bd266b06
- https://git.kernel.org/stable/c/fc8f7752a82f4accb99c0f1a868906ba1eb7b86f
