CVE-2025-40820
📋 TL;DR
This vulnerability allows unauthenticated remote attackers to interfere with TCP connection setup by exploiting improper sequence number validation, potentially causing denial of service. It affects TCP-based services in specific Siemens products when attackers can precisely time spoofed IP packet injection. Only systems running affected Siemens industrial products are vulnerable.
💻 Affected Systems
- Siemens industrial products (specific models not detailed in reference)
⚠️ 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 disruption of TCP-based services leading to operational downtime in industrial environments, potentially affecting critical infrastructure operations.
Likely Case
Intermittent connection failures or degraded performance for TCP services, requiring service restarts to restore normal operation.
If Mitigated
Minimal impact with proper network segmentation and spoofing protections in place, potentially causing only minor connection anomalies.
🎯 Exploit Status
Exploitation requires precise timing and ability to inject spoofed IP packets, making real-world attacks challenging but possible for sophisticated attackers.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Not specified in reference
Vendor Advisory: https://cert-portal.siemens.com/productcert/html/ssa-915282.html
Restart Required: Yes
Instructions:
1. Check Siemens advisory SSA-915282 for affected products. 2. Apply vendor-provided firmware updates. 3. Restart affected devices after patching. 4. Verify patch application through version checks.
🔧 Temporary Workarounds
Network Segmentation
allIsolate affected systems from untrusted networks to prevent packet injection attacks
Ingress Filtering
allImplement BCP38/BCP84 to prevent IP spoofing at network boundaries
🧯 If You Can't Patch
- Implement strict network access controls to limit TCP service exposure
- Deploy intrusion prevention systems with TCP anomaly detection capabilities
🔍 How to Verify
Check if Vulnerable:
Check Siemens advisory SSA-915282 for specific affected product models and versionsCheck Version:
Product-specific - consult device documentation for version check commandsVerify Fix Applied:
Verify firmware version matches patched version specified in Siemens advisory📡 Detection & Monitoring
Log Indicators:
- Unusual TCP connection resets
- Failed connection attempts with abnormal sequence numbers
- TCP SYN flood patterns with spoofed sources
Network Indicators:
- TCP packets with sequence numbers outside expected windows
- IP packets with spoofed source addresses targeting TCP ports
- Abnormal TCP handshake patterns
SIEM Query:
tcp.flags.syn==1 AND tcp.flags.ack==0 AND NOT ip.src IN trusted_networks | stats count by ip.src, tcp.dstport