CVE-2023-53441
📋 TL;DR
A memory leak vulnerability in the Linux kernel's BPF cpumap subsystem allows unprivileged local users to cause denial of service by exhausting kernel memory. The vulnerability occurs when updating CPU map elements triggers improper resource cleanup, leading to unreleased memory allocations. This affects systems running vulnerable Linux kernel versions with BPF enabled.
💻 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 →⚠️ Risk & Real-World Impact
Worst Case
Local attacker could exhaust kernel memory, causing system instability, crashes, or denial of service through resource exhaustion.
Likely Case
Accidental triggering by legitimate BPF programs could cause gradual memory leaks and system performance degradation over time.
If Mitigated
With proper kernel hardening and BPF restrictions, impact is limited to controlled memory consumption without privilege escalation.
🎯 Exploit Status
Exploitation requires local access and BPF capabilities. The vulnerability was discovered through syzkaller fuzzing.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Kernel versions containing fixes: 4369016497319a9635702da010d02af1ebb1849d, a957ac8e0b5ffb5797382a6adbafd005a5f72851, b11a9b4f28cb6ff69ef7e69809e5f7fffeac9030, d26299f50f5ea8f0aeb5d49e659c31f64233c816
Vendor Advisory: https://git.kernel.org/stable/c/4369016497319a9635702da010d02af1ebb1849d
Restart Required: Yes
Instructions:
1. Update to a patched kernel version from your distribution vendor. 2. Reboot the system to load the new kernel. 3. Verify the kernel version after reboot.
🔧 Temporary Workarounds
Disable unprivileged BPF
LinuxPrevents non-root users from using BPF, reducing attack surface
sysctl -w kernel.unprivileged_bpf_disabled=1
echo 'kernel.unprivileged_bpf_disabled = 1' >> /etc/sysctl.d/99-bpf.conf
Restrict BPF system calls
LinuxUse seccomp or other mechanisms to restrict bpf() syscall usage
🧯 If You Can't Patch
- Monitor system memory usage for unusual patterns indicating memory leaks
- Restrict local user access to systems running vulnerable kernels
🔍 How to Verify
Check if Vulnerable:
Check kernel version and compare with distribution's patched versions. Vulnerable if running kernel before the fix commits.Check Version:
uname -rVerify Fix Applied:
Verify kernel version includes one of the fix commits: 436901649731, a957ac8e0b5f, b11a9b4f28cb, or d26299f50f5e📡 Detection & Monitoring
Log Indicators:
- Kernel oops messages related to memory allocation failures
- System logs showing memory exhaustion warnings
- dmesg output with 'memory leak' or 'BUG: memory leak' messages
Network Indicators:
- No network indicators - local vulnerability only
SIEM Query:
Search for kernel panic logs, memory allocation failures, or processes repeatedly calling bpf() system calls