CVE-2025-38139
📋 TL;DR
A kernel memory corruption vulnerability in Linux's netfs subsystem allows attackers to trigger an out-of-bounds read via improper iterator resetting during write retries. This affects Linux systems using the netfs filesystem layer, potentially leading to kernel crashes or privilege escalation. The vulnerability requires local access to trigger.
💻 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 →⚠️ Risk & Real-World Impact
Worst Case
Kernel panic leading to system crash and denial of service, or potential privilege escalation if combined with other vulnerabilities.
Likely Case
Kernel crash causing system instability and denial of service, requiring reboot to restore functionality.
If Mitigated
Limited to denial of service if proper kernel hardening and privilege separation are in place.
🎯 Exploit Status
Exploitation requires local access and ability to trigger write retries in netfs subsystem. No public exploits known at this time.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Kernel versions with commit 4481f7f2b3df123ec77e828c849138f75cff2bf2 or later
Vendor Advisory: https://git.kernel.org/stable/c/4481f7f2b3df123ec77e828c849138f75cff2bf2
Restart Required: Yes
Instructions:
1. Update Linux kernel to version containing fix commit 4481f7f2b3df123ec77e828c849138f75cff2bf2
2. Reboot system to load new kernel
3. Verify kernel version after reboot
🔧 Temporary Workarounds
Disable netfs subsystem
linuxRemove or disable netfs module if not required for system functionality
rmmod netfs
echo 'blacklist netfs' >> /etc/modprobe.d/blacklist.conf
🧯 If You Can't Patch
- Restrict local user access to minimize attack surface
- Implement kernel hardening measures like SELinux/AppArmor to limit damage from potential crashes
🔍 How to Verify
Check if Vulnerable:
Check kernel version and if netfs subsystem is loaded: 'uname -r' and 'lsmod | grep netfs'Check Version:
uname -rVerify Fix Applied:
Verify kernel version contains fix commit: 'uname -r' and check kernel changelog for commit 4481f7f2b3df123ec77e828c849138f75cff2bf2📡 Detection & Monitoring
Log Indicators:
- Kernel panic logs
- KASAN out-of-bounds error messages in dmesg
- System crash/reboot events
Network Indicators:
- None - local vulnerability only
SIEM Query:
source="kernel" AND ("KASAN" OR "slab-out-of-bounds" OR "netfs_retry_write")