CVE-2021-47383
📋 TL;DR
A memory corruption vulnerability in the Linux kernel's framebuffer console driver allows local attackers to trigger out-of-bounds memory access via a specific ioctl sequence. This affects systems with framebuffer console enabled, primarily Linux servers and workstations with local user access.
💻 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 →⚠️ Risk & Real-World Impact
Worst Case
Kernel panic leading to system crash or potential privilege escalation if combined with other vulnerabilities
Likely Case
System instability, denial of service, or kernel crash
If Mitigated
Limited impact due to requirement of local access and specific framebuffer configuration
🎯 Exploit Status
Requires local access and knowledge of specific ioctl sequence to trigger the condition
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Kernel versions with commits 067c694d06040db6f0c65281bb358452ca6d85b9 or later
Vendor Advisory: https://git.kernel.org/stable/c/067c694d06040db6f0c65281bb358452ca6d85b9
Restart Required: Yes
Instructions:
1. Update Linux kernel to patched version from your distribution's repositories. 2. Reboot system to load new kernel.
🔧 Temporary Workarounds
Disable framebuffer console
linuxRemove framebuffer console support to eliminate attack surface
Remove 'vga=' or 'video=' parameters from kernel boot line
Disable fbcon module if built as module
🧯 If You Can't Patch
- Restrict local user access to systems with framebuffer console enabled
- Implement strict access controls and monitoring for ioctl operations on framebuffer devices
🔍 How to Verify
Check if Vulnerable:
Check kernel version and compare with patched versions in git commitsCheck Version:
uname -rVerify Fix Applied:
Verify kernel version is updated and contains the fix commit📡 Detection & Monitoring
Log Indicators:
- Kernel oops messages
- System crash/panic logs
- Unusual ioctl calls to framebuffer devices
Network Indicators:
- None - local vulnerability only
SIEM Query:
Search for kernel panic events or suspicious ioctl operations on /dev/fb* devices🔗 References
- https://git.kernel.org/stable/c/067c694d06040db6f0c65281bb358452ca6d85b9
- https://git.kernel.org/stable/c/3b0c406124719b625b1aba431659f5cdc24a982c
- https://git.kernel.org/stable/c/699d926585daa6ec44be556cdc1ab89e5d54557b
- https://git.kernel.org/stable/c/70aed03b1d5a5df974f456cdc8eedb213c94bb8b
- https://git.kernel.org/stable/c/7e71fcedfda6f7de18f850a6b36e78d78b04476f
- https://git.kernel.org/stable/c/883f7897a25e3ce14a7f274ca4c73f49ac84002a
- https://git.kernel.org/stable/c/8a6a240f52e14356386030d8958ae8b1761d2325
- https://git.kernel.org/stable/c/d570c48dd37dbe8fc6875d4461d01a9554ae2560
- https://git.kernel.org/stable/c/067c694d06040db6f0c65281bb358452ca6d85b9
- https://git.kernel.org/stable/c/3b0c406124719b625b1aba431659f5cdc24a982c
- https://git.kernel.org/stable/c/699d926585daa6ec44be556cdc1ab89e5d54557b
- https://git.kernel.org/stable/c/70aed03b1d5a5df974f456cdc8eedb213c94bb8b
- https://git.kernel.org/stable/c/7e71fcedfda6f7de18f850a6b36e78d78b04476f
- https://git.kernel.org/stable/c/883f7897a25e3ce14a7f274ca4c73f49ac84002a
- https://git.kernel.org/stable/c/8a6a240f52e14356386030d8958ae8b1761d2325
- https://git.kernel.org/stable/c/d570c48dd37dbe8fc6875d4461d01a9554ae2560
