CVE-2025-39927
📋 TL;DR
A race condition vulnerability in the Linux kernel's Ceph filesystem client allows concurrent operations like rename to cause stale parent directory references. This could lead to applying state changes to incorrect directory inodes, potentially causing filesystem corruption or crashes. Affects systems using Ceph filesystem with vulnerable kernel versions.
💻 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 →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 →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
Filesystem corruption leading to data loss or system crashes due to incorrect inode state application
Likely Case
Filesystem inconsistencies, directory structure corruption, or kernel panics during concurrent Ceph operations
If Mitigated
Minor performance impact from additional validation checks with no security compromise
🎯 Exploit Status
Exploitation requires local access and ability to trigger specific race conditions in Ceph operations
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Kernel commits: 15f519e9f883b316d86e2bb6b767a023aafd9d83, 2bfe45987eb346e299d9f763f9cd05f77011519f, db378e6f83ec705c6091c65d482d555edc2b0a72
Vendor Advisory: https://git.kernel.org/stable/c/15f519e9f883b316d86e2bb6b767a023aafd9d83
Restart Required: Yes
Instructions:
1. Update Linux kernel to version containing the fixes. 2. Check with your distribution for backported patches. 3. Reboot system to load new kernel.
🔧 Temporary Workarounds
Disable Ceph filesystem
linuxUnmount Ceph filesystems and disable Ceph client module if not required
umount /path/to/ceph/mount
modprobe -r ceph
🧯 If You Can't Patch
- Avoid concurrent rename operations on Ceph filesystems
- Implement monitoring for filesystem corruption and have recovery procedures ready
🔍 How to Verify
Check if Vulnerable:
Check kernel version and verify if Ceph filesystem is in use: 'mount | grep ceph' and 'uname -r'Check Version:
uname -rVerify Fix Applied:
Verify kernel version includes the fix commits or check with distribution's security advisory📡 Detection & Monitoring
Log Indicators:
- Kernel panic messages related to Ceph
- Filesystem corruption errors in dmesg
- Ceph client error messages
Network Indicators:
- Unusual Ceph MDS protocol errors
SIEM Query:
source="kernel" AND ("ceph" OR "Ceph") AND ("panic" OR "corrupt" OR "error")