CVE-2023-39179
📋 TL;DR
CVE-2023-39179 is an out-of-bounds read vulnerability in the Linux kernel's ksmbd SMB2 module that allows attackers to read sensitive kernel memory. This affects Linux systems with ksmbd enabled, potentially exposing credentials, encryption keys, or other sensitive data. Only systems using the ksmbd kernel module for SMB file sharing are vulnerable.
💻 Affected Systems
- Linux kernel ksmbd module
📦 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 →⚠️ Risk & Real-World Impact
Worst Case
Complete kernel memory disclosure leading to credential theft, privilege escalation, or system compromise
Likely Case
Disclosure of sensitive kernel memory contents including potentially authentication tokens or file data
If Mitigated
Limited information disclosure with no direct code execution if proper network segmentation exists
🎯 Exploit Status
Requires SMB client access to trigger the vulnerable read request. No public exploit code available as of knowledge cutoff.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Linux kernel 6.5.7, 6.1.49, 5.15.128 and later
Vendor Advisory: https://access.redhat.com/security/cve/CVE-2023-39179
Restart Required: Yes
Instructions:
1. Update Linux kernel to patched version. 2. Rebuild and reload ksmbd module if using DKMS. 3. Reboot system to load new kernel.
🔧 Temporary Workarounds
Disable ksmbd module
linuxUnload the ksmbd kernel module to prevent exploitation
sudo rmmod ksmbd
echo 'blacklist ksmbd' | sudo tee /etc/modprobe.d/ksmbd-blacklist.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 entirely if SMB sharing not required
- Implement strict network segmentation to isolate SMB servers from untrusted networks
🔍 How to Verify
Check if Vulnerable:
Check if ksmbd module is loaded: lsmod | grep ksmbd. If loaded and kernel version is vulnerable, system is at risk.Check Version:
uname -rVerify Fix Applied:
Verify kernel version is patched: uname -r. Check that version is 6.5.7, 6.1.49, 5.15.128 or later.📡 Detection & Monitoring
Log Indicators:
- Kernel oops messages related to ksmbd
- SMB2 read request anomalies in system logs
Network Indicators:
- Unusual SMB2 read request patterns
- Multiple failed SMB connection attempts
SIEM Query:
source="kernel" AND "ksmbd" AND ("oops" OR "panic" OR "BUG")