CVE-2020-14381
📋 TL;DR
This CVE describes a use-after-free vulnerability in the Linux kernel's futex implementation. A local attacker can exploit this flaw to corrupt system memory or escalate privileges when creating a futex on a filesystem that is about to be unmounted. This affects Linux systems with vulnerable kernel versions.
💻 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
Local privilege escalation to root, system memory corruption leading to kernel panic or complete system compromise.
Likely Case
Local privilege escalation allowing an attacker to gain root access on the affected system.
If Mitigated
Limited impact if proper access controls restrict local user accounts and filesystem unmounting operations.
🎯 Exploit Status
Exploitation requires local access and specific timing conditions during filesystem unmounting. Proof-of-concept code has been published.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Linux kernel 5.8.8 and later
Vendor Advisory: https://bugzilla.redhat.com/show_bug.cgi?id=1874311
Restart Required: Yes
Instructions:
1. Update Linux kernel to version 5.8.8 or later. 2. For Red Hat/CentOS systems: Apply kernel security updates via yum update kernel. 3. Reboot the system to load the patched kernel.
🔧 Temporary Workarounds
Restrict filesystem unmounting
linuxLimit which users can unmount filesystems to reduce attack surface
chmod 700 /bin/umount
setfacl -m u:root:rwx /bin/umount
Disable unnecessary user accounts
linuxReduce number of local users who could potentially exploit the vulnerability
usermod -L username
passwd -l username
🧯 If You Can't Patch
- Implement strict access controls to limit local user accounts
- Monitor for suspicious privilege escalation attempts and filesystem unmount operations
🔍 How to Verify
Check if Vulnerable:
Check kernel version: uname -r. If version is earlier than 5.8.8, system is vulnerable.Check Version:
uname -rVerify Fix Applied:
After patching and reboot, verify kernel version with uname -r shows 5.8.8 or later.📡 Detection & Monitoring
Log Indicators:
- Kernel panic logs
- Unexpected privilege escalation in audit logs
- Suspicious filesystem unmount operations
Network Indicators:
- None - this is a local vulnerability
SIEM Query:
source="kernel" AND ("panic" OR "oops") OR source="audit" AND "privilege" AND "escalation"🔗 References
- https://bugzilla.redhat.com/show_bug.cgi?id=1874311
- https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=8019ad13ef7f64be44d4f892af9c840179009254
- https://bugzilla.redhat.com/show_bug.cgi?id=1874311
- https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=8019ad13ef7f64be44d4f892af9c840179009254
