What is CVE-2025-66631?

CVE-2025-66631 is a critical-severity vulnerability in Cslanet Csla .Net, classified under Deserialization of Untrusted Data. CVSS score: 9.8/10. Published 2025-12-09.

How severe is CVE-2025-66631?

Critical severity. CVSS v3 base score is 9.8 out of 10.

Deserialization in Cslanet Csla .Net

CVE-2025-66631

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.

Vulnerability class: Insecure Deserialization

EPSS: 0.006 (44.6th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

Affected products

Cslanet Csla_.net
Marimerllc Csla — versions < 6.0.0

Weakness classification (CWE)

CWE-502 — Deserialization of Untrusted Data

References

security-advisories@github.com (x_refsource_CONFIRM, Mitigation, Vendor Advisory)
security-advisories@github.com (x_refsource_MISC, Issue Tracking)
security-advisories@github.com (Patch, x_refsource_MISC, Issue Tracking)

Frequently asked questions

What is CVE-2025-66631?: CVE-2025-66631 is a critical-severity vulnerability in Cslanet Csla .Net, classified under Deserialization of Untrusted Data. CVSS score: 9.8/10. Published 2025-12-09.
How severe is CVE-2025-66631?: Critical severity. CVSS v3 base score is 9.8 out of 10.