CVE-2022-50021
📋 TL;DR
A use-after-free vulnerability in the Linux kernel's ext4 filesystem allows attackers to trigger a kernel panic (system crash) by exploiting corrupted filesystems. This affects Linux systems using ext4 with bigalloc feature enabled. Attackers with local access can cause denial of service.
💻 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 →⚠️ Risk & Real-World Impact
Worst Case
Kernel panic leading to complete system crash and denial of service, potentially requiring physical reboot.
Likely Case
Local denial of service through kernel panic, disrupting system availability.
If Mitigated
Minimal impact with proper kernel hardening and filesystem integrity checks.
🎯 Exploit Status
Syzkaller fuzzer discovered the vulnerability. Exploitation requires local access and ability to create/manipulate filesystems.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Linux kernel stable releases containing the fix commits
Vendor Advisory: https://git.kernel.org/stable/c/1e1c2b86ef86a8477fd9b9a4f48a6bfe235606f6
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 bigalloc feature
linuxMount ext4 filesystems without bigalloc feature to avoid the vulnerable code path
mount -t ext4 -o no_bigalloc /dev/device /mountpoint
🧯 If You Can't Patch
- Restrict local user access to prevent untrusted users from mounting or manipulating filesystems
- Implement strict filesystem integrity monitoring and alert on corruption attempts
🔍 How to Verify
Check if Vulnerable:
Check kernel version and if ext4 with bigalloc is in use: 'uname -r' and 'mount | grep ext4'Check Version:
uname -rVerify Fix Applied:
Verify kernel version is updated and check dmesg for absence of ext4-related crashes📡 Detection & Monitoring
Log Indicators:
- Kernel panic messages in dmesg/system logs
- ext4 filesystem error messages
- System crash/reboot events
Network Indicators:
- None - local vulnerability only
SIEM Query:
source="kernel" AND ("ext4" OR "kernel panic" OR "BUG")