CVE-2023-53481
📋 TL;DR
This CVE describes a kernel-level infinite loop vulnerability in the Linux UBI (Unsorted Block Images) subsystem. When wear-leveling operations fail due to flash memory faults, the ubi_wl_put_peb() function can enter an infinite loop, causing 100% CPU consumption and potential denial of service. This affects systems using UBI/UBIFS on flash storage, particularly embedded Linux devices.
💻 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
Complete system unresponsiveness due to 100% CPU consumption in kernel thread, requiring hard reboot and potential filesystem corruption.
Likely Case
Denial of service on affected storage operations, causing system instability and performance degradation until reboot.
If Mitigated
Minimal impact if systems are patched or don't use UBI/UBIFS on flash storage.
🎯 Exploit Status
Reproducer available in linked kernel commit. Requires ability to trigger wear-leveling operations on UBI volumes, typically needs local access or control of storage operations.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Patched in stable kernel versions via commits: 3afaaf6f5867dc4ad383808d4053f428ec7b867d, 4d57a7333e26040f2b583983e1970d9d460e56b0, 5af1c643184a5d09ff5b3f334077a4d0a163c677, 8a18856e074479bd050b01e688c58defadce7ab0, b40d2fbf47af58377e898b5062077a47bb28a132
Vendor Advisory: https://git.kernel.org/stable/c/3afaaf6f5867dc4ad383808d4053f428ec7b867d
Restart Required: Yes
Instructions:
1. Update Linux kernel to patched version from your distribution. 2. For embedded systems: rebuild kernel with patches from stable tree. 3. Reboot system after kernel update.
🔧 Temporary Workarounds
Disable UBI/UBIFS if not needed
linuxRemove UBI/UBIFS kernel modules and disable in kernel config if not required for your system
rmmod ubifs
rmmod ubi
echo 'blacklist ubifs' >> /etc/modprobe.d/blacklist.conf
echo 'blacklist ubi' >> /etc/modprobe.d/blacklist.conf
Monitor for high CPU in ubifs_bgt threads
linuxSet up monitoring to detect and alert on 100% CPU usage by ubifs_bgt threads
while true; do ps aux | grep -E 'ubifs_bgt.*100\.0'; sleep 10; done
🧯 If You Can't Patch
- Implement strict access controls to limit who can perform storage operations on UBI volumes
- Monitor system logs for flash I/O errors and UBI wear-leveling failures that could trigger the condition
🔍 How to Verify
Check if Vulnerable:
Check if UBI/UBIFS modules are loaded and kernel version is unpatched: lsmod | grep -E 'ubi|ubifs' && uname -rCheck Version:
uname -rVerify Fix Applied:
Verify kernel version is patched and test with reproducer from kernel commit if available📡 Detection & Monitoring
Log Indicators:
- Kernel logs showing UBI errors, flash I/O failures, wear-leveling failures
- System logs showing high CPU usage by ubifs_bgt threads
Network Indicators:
- None - local vulnerability only
SIEM Query:
process.name:"ubifs_bgt*" AND process.cpu_usage:>95🔗 References
- https://git.kernel.org/stable/c/3afaaf6f5867dc4ad383808d4053f428ec7b867d
- https://git.kernel.org/stable/c/4d57a7333e26040f2b583983e1970d9d460e56b0
- https://git.kernel.org/stable/c/5af1c643184a5d09ff5b3f334077a4d0a163c677
- https://git.kernel.org/stable/c/8a18856e074479bd050b01e688c58defadce7ab0
- https://git.kernel.org/stable/c/b40d2fbf47af58377e898b5062077a47bb28a132
- https://git.kernel.org/stable/c/b5be23f6ae610bdb262160a1f294afee6d0e6a69
- https://git.kernel.org/stable/c/cc4bc532acda66189bddc03b3fe1ad689d9a48a2
- https://git.kernel.org/stable/c/f006f596fe851c3b6aae60b79f89f89f0e515d2f
