CVE-2025-67433
📋 TL;DR
A heap buffer overflow vulnerability in Open TFTP Server MultiThreaded v1.7 allows attackers to cause a Denial of Service (DoS) by sending a specially crafted DATA packet. This affects anyone running the vulnerable version of this TFTP server software. The vulnerability is in the processRequest function and can be triggered remotely.
💻 Affected Systems
- Open TFTP Server MultiThreaded
⚠️ 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 server crash leading to service unavailability, potentially allowing for remote code execution if the heap overflow can be controlled precisely.
Likely Case
Denial of Service causing the TFTP server to crash, disrupting file transfer services.
If Mitigated
Minimal impact if the server is behind network controls or not exposed to untrusted networks.
🎯 Exploit Status
Exploitation requires crafting a specific DATA packet but no authentication is needed. The references show analysis but no public exploit code.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Check for updates beyond v1.7 on SourceForge
Vendor Advisory: https://sourceforge.net/projects/tftp-server/
Restart Required: Yes
Instructions:
1. Visit the SourceForge project page. 2. Download the latest version. 3. Stop the TFTP server service. 4. Install the updated version. 5. Restart the service.
🔧 Temporary Workarounds
Network Segmentation
allRestrict TFTP server access to trusted networks only using firewall rules.
Service Disablement
allTemporarily disable the TFTP server if not critically needed.
🧯 If You Can't Patch
- Implement strict network access controls to limit TFTP server exposure to only necessary clients.
- Monitor server logs for unusual DATA packet patterns or crashes and have incident response procedures ready.
🔍 How to Verify
Check if Vulnerable:
Check the server version by examining the executable properties or running with --version flag if available.Check Version:
On Windows: Check file properties of tftpserver.exe. On Linux: Run ./tftpserver --version or similar.Verify Fix Applied:
Verify the installed version is newer than v1.7 and test with normal TFTP operations.📡 Detection & Monitoring
Log Indicators:
- Server crash logs
- Error messages related to buffer overflow or memory corruption in TFTP logs
Network Indicators:
- Unusually large or malformed TFTP DATA packets on UDP port 69
SIEM Query:
source="tftp.log" AND ("crash" OR "overflow" OR "memory")