CVE-2026-54781
High
Description
CoreWCF is a port of the service side of Windows Communication Foundation (WCF) to .NET Core. Prior to 1.8.1 and 1.9.1, CoreWCF SAML token validation does not enforce SubjectConfirmation method URIs or holder-of-key proof keys in SamlSecurityTokenHandler, allowing holder-of-key downgrade or custom confirmation method assertions to authenticate a subject without proving authority over the assertion. This issue is fixed in versions 1.8.1 and 1.9.1.
SeverityHigh
CVSS7.4
Exploit probability—
ProductCorewcf.primitives
PublishedJul 8, 2026
First seenJul 8, 2026
Weakness typeCWE-287Improper authenticationCWE-345CWE-345
How to fix
Update
- CoreWCF.Primitives1.8.1, 1.9.1 or later
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| CoreWCF.PrimitivesNuGet | v < 1.8.1, 1.9.0 ≤ v < 1.9.1 | 1.8.1, 1.9.1 |
Check your version
Choose the product and enter the version you run to see whether it falls in the affected range.
In the Intelligence 360 plan
Attack Surface Management
See the assets tied to your domains, the technologies they run and known vulnerabilities in one list.