CVE-2023-53230
📋 TL;DR
This CVE describes a memory leak vulnerability in the Linux kernel's SMB client implementation. When mounting SMB shares via cifs_smb3_do_mount(), the kernel may fail to properly free allocated memory for the cifs_sb structure. This affects Linux systems using the CIFS/SMB client to mount network shares.
💻 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 →⚠️ Risk & Real-World Impact
Worst Case
Sustained exploitation could lead to kernel memory exhaustion, causing system instability, denial of service, or kernel crashes.
Likely Case
Repeated mount operations may gradually consume kernel memory, potentially leading to performance degradation or system instability over time.
If Mitigated
With proper monitoring and limited mount operations, impact is minimal to none.
🎯 Exploit Status
Exploitation requires ability to trigger SMB mount operations. No known public exploits.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Multiple stable kernel versions with fixes: 12c30f33cc6769bf411088a2872843c4f9ea32f9, 945f4a7aff84fde1f825d17a5050880345da3228, 9850867042674361f455ea8901375cff5b800be5, eb79f8dfba343667f9a82a252743f4e8f67ce420
Vendor Advisory: https://git.kernel.org/stable/c/12c30f33cc6769bf411088a2872843c4f9ea32f9
Restart Required: Yes
Instructions:
1. Update Linux kernel to patched version. 2. Check distribution-specific security advisories. 3. Reboot system after kernel update.
🔧 Temporary Workarounds
Restrict SMB mount privileges
allLimit which users can mount SMB shares to reduce attack surface
# Use sudoers or similar to restrict mount commands
# Example: Remove cifs mount capabilities from non-admin users
Monitor kernel memory usage
allImplement monitoring for unusual kernel memory consumption patterns
# Monitor slabinfo for cifs_sb allocations
cat /proc/slabinfo | grep -i cifs
# Monitor overall memory
free -h
vmstat 1
🧯 If You Can't Patch
- Implement strict access controls on SMB mount operations
- Monitor system for memory exhaustion symptoms and restart affected services if detected
🔍 How to Verify
Check if Vulnerable:
Check kernel version and if CIFS/SMB client is in use. Vulnerable if using unpatched kernel with CIFS support.Check Version:
uname -rVerify Fix Applied:
Verify kernel version includes one of the referenced patches. Check /proc/version or uname -r.📡 Detection & Monitoring
Log Indicators:
- Kernel oops messages
- Out of memory errors in dmesg
- Repeated SMB mount failures
Network Indicators:
- Unusual SMB mount requests from internal systems
SIEM Query:
Search for: 'kernel: Out of memory' OR 'kernel: cifs' AND 'error' OR 'failed' in system logs