CVE-2025-68817
📋 TL;DR
This CVE describes a use-after-free vulnerability in the Linux kernel's ksmbd SMB server module. Under high concurrency conditions, a tree-connection object can be freed while another process still holds a reference to it, potentially leading to memory corruption. This affects systems running Linux kernels with ksmbd 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 →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, system crash, or potential arbitrary code execution with kernel privileges leading to complete system compromise.
Likely Case
System instability, crashes, or denial of service affecting SMB file sharing functionality.
If Mitigated
Limited impact if ksmbd is disabled or not exposed to untrusted networks.
🎯 Exploit Status
Requires specific high-concurrency conditions and SMB access. No public exploits known at this time.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Patches available in stable kernel trees (see git.kernel.org references)
Vendor Advisory: https://git.kernel.org/stable/c/063cbbc6f595ea36ad146e1b7d2af820894beb21
Restart Required: Yes
Instructions:
1. Update to a patched kernel version from your distribution vendor. 2. Reboot the system to load the new kernel.
🔧 Temporary Workarounds
Disable ksmbd module
linuxUnload the ksmbd kernel module if not required
sudo rmmod ksmbd
echo 'blacklist ksmbd' | sudo tee /etc/modprobe.d/blacklist-ksmbd.conf
Restrict SMB access
linuxUse firewall rules to limit SMB access to trusted networks only
sudo iptables -A INPUT -p tcp --dport 445 -s TRUSTED_NETWORK -j ACCEPT
sudo iptables -A INPUT -p tcp --dport 445 -j DROP
🧯 If You Can't Patch
- Disable ksmbd module if SMB server functionality is not required
- Implement strict network segmentation and limit SMB access to essential systems only
🔍 How to Verify
Check if Vulnerable:
Check if ksmbd module is loaded: lsmod | grep ksmbdCheck Version:
uname -rVerify Fix Applied:
Check kernel version after update and verify ksmbd module version matches patched kernel📡 Detection & Monitoring
Log Indicators:
- Kernel panic logs
- ksmbd crash messages in dmesg
- SMB connection failures
Network Indicators:
- Unusual SMB traffic patterns, especially high concurrent connections
SIEM Query:
source="kernel" AND ("panic" OR "Oops" OR "ksmbd")🔗 References
- https://git.kernel.org/stable/c/063cbbc6f595ea36ad146e1b7d2af820894beb21
- https://git.kernel.org/stable/c/21a3d01fc6db5129f81edb0ab7cb94fd758bcbea
- https://git.kernel.org/stable/c/446beed646b2e426dd53d27358365f8678e1dd01
- https://git.kernel.org/stable/c/b39a1833cc4a2755b02603eec3a71a85e9dff926
- https://git.kernel.org/stable/c/d092de8a26c952379ded8e6b0bda31d89befac1a
- https://git.kernel.org/stable/c/d64977495e44855f2b28d8ce56107c963a7a50e4
