CVE-2024-50220
📋 TL;DR
A race condition vulnerability in the Linux kernel's fork process where userfaultfd (UFFD) handlers can access incomplete or inconsistent virtual memory address spaces during fork operations when errors occur. This affects Linux systems using userfaultfd functionality, potentially allowing local attackers to cause crashes or memory corruption.
💻 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 →⚠️ Risk & Real-World Impact
Worst Case
Local privilege escalation or kernel panic leading to denial of service through memory corruption of kernel structures.
Likely Case
Kernel crash or system instability when userfaultfd handlers access inconsistent memory states during fork errors.
If Mitigated
No impact if userfaultfd is not enabled or the system is patched.
🎯 Exploit Status
Exploitation requires local access and knowledge of userfaultfd API. The vulnerability involves race conditions during fork errors, making reliable exploitation challenging.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Kernel versions containing commits 92b472945dbf8abc020e9259c0088026f7027dfc and f64e67e5d3a45a4a04286c47afade4b518acd47b
Vendor Advisory: https://git.kernel.org/stable/c/92b472945dbf8abc020e9259c0088026f7027dfc
Restart Required: Yes
Instructions:
1. Update Linux kernel to patched version from your distribution vendor. 2. Reboot system to load new kernel. 3. Verify kernel version matches patched release.
🔧 Temporary Workarounds
Disable userfaultfd
linuxPrevent exploitation by disabling userfaultfd functionality system-wide
sysctl -w vm.unprivileged_userfaultfd=0
echo 0 > /proc/sys/vm/unprivileged_userfaultfd
Restrict userfaultfd to privileged users
linuxLimit userfaultfd usage to root or privileged processes only
sysctl -w vm.userfaultfd=1
echo 1 > /proc/sys/vm/userfaultfd
🧯 If You Can't Patch
- Disable userfaultfd functionality via sysctl
- Implement strict access controls to prevent unprivileged users from using userfaultfd
🔍 How to Verify
Check if Vulnerable:
Check kernel version and compare with patched versions from your distribution. Check if userfaultfd is enabled: cat /proc/sys/vm/unprivileged_userfaultfdCheck Version:
uname -rVerify Fix Applied:
Verify kernel version includes the fix commits. Test userfaultfd functionality to ensure system stability.📡 Detection & Monitoring
Log Indicators:
- Kernel panic logs
- OOM killer activity during fork operations
- Userfaultfd-related error messages in dmesg
Network Indicators:
- None - local vulnerability only
SIEM Query:
Search for: 'kernel panic', 'BUG:', 'general protection fault' in system logs during fork operations