CVE-2023-32253
📋 TL;DR
This vulnerability in the Linux kernel's ksmbd component allows attackers to trigger a deadlock by sending multiple concurrent session setup requests. This can lead to denial of service conditions affecting systems running vulnerable kernel versions with ksmbd enabled. The impact is limited to availability rather than data compromise.
💻 Affected Systems
- Linux kernel
⚠️ 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
Complete denial of service for the ksmbd service, potentially affecting SMB file sharing functionality until system restart.
Likely Case
Temporary service disruption or performance degradation for SMB file sharing services.
If Mitigated
Minimal impact if ksmbd is disabled or properly patched.
🎯 Exploit Status
Exploitation requires sending multiple concurrent SMB session setup requests, which is relatively straightforward.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Kernel versions with fix backported (check specific distribution)
Vendor Advisory: https://access.redhat.com/security/cve/CVE-2023-32253
Restart Required: Yes
Instructions:
1. Update kernel package via distribution's package manager. 2. Reboot system to load new kernel. 3. Verify ksmbd service is running with patched kernel.
🔧 Temporary Workarounds
Disable ksmbd module
LinuxPrevent loading of the vulnerable ksmbd kernel module
echo 'blacklist ksmbd' >> /etc/modprobe.d/blacklist-ksmbd.conf
rmmod ksmbd
Block SMB ports at firewall
LinuxPrevent external access to ksmbd service
iptables -A INPUT -p tcp --dport 445 -j DROP
iptables -A INPUT -p tcp --dport 139 -j DROP
🧯 If You Can't Patch
- Disable ksmbd service if not required for operations
- Implement network segmentation to restrict access to ksmbd services
🔍 How to Verify
Check if Vulnerable:
Check if ksmbd module is loaded: lsmod | grep ksmbd. If loaded, check kernel version against patched versions for your distribution.Check Version:
uname -rVerify Fix Applied:
Verify kernel version after update matches patched version from vendor advisory and ksmbd service remains functional.📡 Detection & Monitoring
Log Indicators:
- Multiple failed SMB session setup attempts in short timeframe
- ksmbd service crash or restart logs
- System logs showing deadlock warnings
Network Indicators:
- Unusual volume of SMB session setup requests from single source
- SMB service becoming unresponsive
SIEM Query:
source="*kernel*" AND "ksmbd" AND ("deadlock" OR "panic" OR "oops")