CVE-2025-71220
📋 TL;DR
A Linux kernel vulnerability in the SMB server component (ksmbd) where error handling fails to properly close RPC sessions when certain memory operations fail. This affects Linux systems running ksmbd SMB server functionality, potentially leading to resource exhaustion or denial of service.
💻 Affected Systems
- Linux kernel with ksmbd SMB server module
⚠️ Manual Verification Required
This CVE does not have specific version information in our database, so automatic vulnerability detection cannot determine if your system is affected.
Why? The CVE database entry doesn't specify which versions are vulnerable (no version ranges provided by the vendor/NVD).
🔒 Custom verification scripts are available for registered users. Sign up free to download automated test scripts.
- Review the CVE details at NVD
- Check vendor security advisories for your specific version
- Test if the vulnerability is exploitable in your environment
- Consider updating to the latest version as a precaution
⚠️ Risk & Real-World Impact
Worst Case
Resource exhaustion leading to kernel panic or system crash, potentially disrupting SMB services and affecting all users of the system.
Likely Case
Memory leak causing gradual performance degradation of SMB services, potentially leading to service unavailability for SMB clients.
If Mitigated
Minimal impact with proper monitoring and resource limits in place, though SMB service interruptions may still occur.
🎯 Exploit Status
Exploitation requires ability to trigger specific error conditions in SMB pipe creation, likely requiring authenticated access to SMB services.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Linux kernel versions with commits 04dd114b682a4ccaeba2c2bad049c8b50ce740d8 and related fixes
Vendor Advisory: https://git.kernel.org/stable/c/04dd114b682a4ccaeba2c2bad049c8b50ce740d8
Restart Required: No
Instructions:
1. Update Linux kernel to patched version from your distribution vendor. 2. If using mainline kernel, apply commits from git.kernel.org references. 3. Rebuild and load ksmbd module if using custom kernel.
🔧 Temporary Workarounds
Disable ksmbd module
allPrevent loading of vulnerable ksmbd SMB server module
echo 'blacklist ksmbd' >> /etc/modprobe.d/blacklist-ksmbd.conf
rmmod ksmbd
Use alternative SMB server
LinuxReplace ksmbd with samba or other SMB server implementation
apt-get install samba
systemctl disable ksmbd
systemctl enable smbd
🧯 If You Can't Patch
- Implement strict access controls to limit SMB connections to trusted clients only
- Monitor system memory usage and implement automatic restart thresholds for ksmbd service
🔍 How to Verify
Check if Vulnerable:
Check if ksmbd module is loaded: lsmod | grep ksmbd. If loaded, check kernel version against patched versions.Check Version:
uname -rVerify Fix Applied:
Verify kernel version includes fix commits or check with distribution vendor for patched kernel version.📡 Detection & Monitoring
Log Indicators:
- Kernel logs showing memory allocation failures
- ksmbd logs showing pipe creation errors
- System logs showing high memory usage by kernel
Network Indicators:
- Increased SMB connection failures
- SMB service becoming unresponsive
SIEM Query:
source="kernel" AND ("ksmbd" OR "SMB") AND ("error" OR "fail" OR "panic")🔗 References
- https://git.kernel.org/stable/c/04dd114b682a4ccaeba2c2bad049c8b50ce740d8
- https://git.kernel.org/stable/c/2b7b4df87fe6f2db6ee45f475de6b37b8b8e5d29
- https://git.kernel.org/stable/c/7c28f8eef5ac5312794d8a52918076dcd787e53b
- https://git.kernel.org/stable/c/a2c68e256fb7a4ac34154c6e865a1389acca839f
- https://git.kernel.org/stable/c/ac18761b530b5dd40f59af8a25902282e5512854
- https://git.kernel.org/stable/c/fdda836fcee6fdbcccc24e3679097efb583f581f
