CVE-2025-66631 CSLA .NET is vulnerable to Remote Code Execution via WcfProxy
Remote code execution via insecure deserialization in WcfProxy allows attackers to execute arbitrary code in applications using CSLA .NET.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2025-66631?
CVE-2025-66631 is a high-severity unsafe deserialization vulnerability in MarimerLLC csla, published on 9 Dec 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
CSLA .NET is a framework designed for the development of reusable, object-oriented business layers for applications. Versions 5.5.4 and below allow the use of WcfProxy. WcfProxy uses the now-obsolete NetDataContractSerializer (NDCS) and is vulnerable to remote code execution during deserialization. This vulnerability is fixed in version 6.0.0. To workaround this issue, remove the WcfProxy in data portal configurations.
Weakness: CWE-502
Which versions are affected by CVE-2025-66631?
2 open source packages ship an affected version, including Csla. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
Csla NuGet | All versions | 6.0.0 |
Csla NuGet | All versions | 6.0.0 |
Products include Cslanet Csla .Net.
How do I fix CVE-2025-66631?
Upgrade Csla to 6.0.0 or later.
Upgrade, and only deserialise data from trusted sources or with an allow-list of types. More about Unsafe deserialization.
Is CVE-2025-66631 being exploited?
There is no known exploitation of CVE-2025-66631 in the wild and no public exploit code.
Sources
Also known as GHSA-wq34-7f4g-953v.