CVE-2025-39879
📋 TL;DR
A NULL pointer dereference vulnerability in the Linux kernel's Ceph filesystem driver can cause kernel crashes when handling write operations. This affects systems using Ceph storage with vulnerable kernel versions, potentially leading to denial of service.
💻 Affected Systems
- Linux kernel with Ceph filesystem support
📦 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
Kernel panic leading to system crash and denial of service, requiring physical or remote reboot.
Likely Case
System instability or crash when Ceph write operations encounter specific conditions, causing service disruption.
If Mitigated
No impact if patched or if Ceph filesystem is not in use.
🎯 Exploit Status
Requires ability to trigger specific Ceph write operations. Crash can be reproduced by modifying ceph_check_page_before_write() return value.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Kernel versions with commits 289b6615cf553d98509a9b273195d9936da1cfb2 or cce7c15faaac79b532a07ed6ab8332280ad83762
Vendor Advisory: https://git.kernel.org/stable/c/289b6615cf553d98509a9b273195d9936da1cfb2
Restart Required: Yes
Instructions:
1. Update Linux kernel to patched version. 2. Reboot system. 3. Verify kernel version after reboot.
🔧 Temporary Workarounds
Disable Ceph filesystem
allUnmount Ceph filesystems to prevent exploitation
umount /path/to/ceph/mount
systemctl stop ceph.target
🧯 If You Can't Patch
- Avoid using Ceph filesystem for write-intensive operations
- Implement monitoring for kernel crashes and have recovery procedures ready
🔍 How to Verify
Check if Vulnerable:
Check kernel version and if Ceph filesystem is in use: 'uname -r' and 'mount | grep ceph'Check Version:
uname -rVerify Fix Applied:
Verify kernel version includes fix commits: 'uname -r' and check kernel changelog📡 Detection & Monitoring
Log Indicators:
- Kernel panic messages
- NULL pointer dereference in kernel logs
- Ceph-related crash dumps
Network Indicators:
- Unusual Ceph client disconnections
SIEM Query:
source="kernel" AND ("NULL pointer dereference" OR "ceph_writepages_start" OR "kernel panic")