CVE-2025-66631
📋 TL;DR
CVE-2025-66631 is a remote code execution vulnerability in CSLA .NET framework versions 5.5.4 and below. It allows attackers to execute arbitrary code by exploiting insecure deserialization in the WcfProxy component. Applications using CSLA .NET with WcfProxy in their data portal configurations are affected.
💻 Affected Systems
- CSLA .NET
⚠️ 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
Full system compromise allowing attacker to execute arbitrary code with application privileges, potentially leading to data theft, system takeover, or lateral movement.
Likely Case
Remote code execution leading to application compromise, data exfiltration, or deployment of malware/ransomware.
If Mitigated
Limited impact if proper network segmentation and least privilege principles are applied, though RCE still poses significant risk.
🎯 Exploit Status
Exploitation requires sending malicious serialized data to vulnerable endpoints. The vulnerability is in deserialization logic, making exploitation straightforward for attackers familiar with .NET serialization attacks.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 6.0.0
Vendor Advisory: https://github.com/MarimerLLC/csla/security/advisories/GHSA-wq34-7f4g-953v
Restart Required: Yes
Instructions:
1. Update CSLA .NET to version 6.0.0 or later. 2. Update all project references to use the new version. 3. Rebuild and redeploy applications. 4. Test functionality to ensure compatibility with version 6.0.0 changes.
🔧 Temporary Workarounds
Remove WcfProxy Configuration
allDisable the vulnerable WcfProxy component by removing it from data portal configurations.
Edit application configuration files to remove or comment out WcfProxy references in data portal settings.
🧯 If You Can't Patch
- Implement strict network controls to limit access to vulnerable endpoints
- Deploy application firewalls with deserialization attack detection rules
🔍 How to Verify
Check if Vulnerable:
Check if application uses CSLA .NET version 5.5.4 or below AND has WcfProxy configured in data portal settings.Check Version:
Check project references in .csproj files or assembly version in deployed binaries.Verify Fix Applied:
Verify CSLA .NET version is 6.0.0 or higher, and confirm WcfProxy is not present in configurations.📡 Detection & Monitoring
Log Indicators:
- Unusual deserialization errors
- Unexpected process creation from application
- Abnormal network connections from application process
Network Indicators:
- Malformed serialized data sent to application endpoints
- Unusual payloads in WCF communications
SIEM Query:
Process creation events from CSLA .NET application processes OR network traffic to application ports containing serialized .NET objects