CVE-2025-71151
📋 TL;DR
A memory and information leak vulnerability exists in the Linux kernel's CIFS/SMB3 client implementation. When smb3_sync_session_ctx_passwords() fails during reconfiguration, sensitive password buffers aren't properly cleaned up, potentially exposing credentials in memory. This affects Linux systems using CIFS/SMB3 file sharing.
💻 Affected Systems
- Linux kernel CIFS/SMB3 client
📦 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 →⚠️ Risk & Real-World Impact
Worst Case
Sensitive password information could be extracted from kernel memory by local attackers, potentially leading to credential theft and lateral movement within the network.
Likely Case
Local attackers with access to kernel memory could extract password information, though exploitation requires specific conditions where password reconfiguration fails.
If Mitigated
With proper access controls and memory protection mechanisms, the risk is limited to authorized users who can already access kernel memory.
🎯 Exploit Status
Exploitation requires local access and ability to trigger the specific error condition in smb3_sync_session_ctx_passwords() during password reconfiguration.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Patched in stable kernel commits: 5679cc90bb5415801fa29041da0319d9e15d295d, bb82aaee16907dc4d0b9b0ca7953ceb3edc328c6, bc390b2737205163e48cc1655f6a0c8cd55b02fc, cb6d5aa9c0f10074f1ad056c3e2278ad2cc7ec8d
Vendor Advisory: https://git.kernel.org/stable/c/5679cc90bb5415801fa29041da0319d9e15d295d
Restart Required: Yes
Instructions:
1. Update to a patched kernel version containing the fix commits. 2. Reboot the system to load the new kernel. 3. Verify the fix by checking kernel version and ensuring CIFS/SMB3 functionality works correctly.
🔧 Temporary Workarounds
Disable CIFS/SMB3 client
linuxPrevent use of the vulnerable CIFS/SMB3 client module
modprobe -r cifs
echo 'blacklist cifs' >> /etc/modprobe.d/blacklist.conf
🧯 If You Can't Patch
- Restrict local user access to systems using CIFS/SMB3 shares
- Implement strict access controls and monitoring for systems that must use CIFS/SMB3 functionality
🔍 How to Verify
Check if Vulnerable:
Check if your kernel version includes the fix commits or if you're using an unpatched kernel with CIFS/SMB3 functionalityCheck Version:
uname -rVerify Fix Applied:
Verify kernel version includes the fix commits and test CIFS/SMB3 password reconfiguration functionality📡 Detection & Monitoring
Log Indicators:
- Kernel logs showing CIFS/SMB3 password reconfiguration failures
- System logs showing unexpected memory access patterns
Network Indicators:
- Unusual CIFS/SMB3 authentication patterns
- Multiple failed password reconfiguration attempts
SIEM Query:
source="kernel" AND ("cifs" OR "smb3") AND ("password" OR "reconfigure" OR "failed")