CVE-2026-54784
High
Description
CoreWCF is a port of the service side of Windows Communication Foundation (WCF) to .NET Core. In version 1.9.0, CoreWCF SPNEGO SecurityContextToken negotiation can expose the proof key recovered from the RSTR when TransportWithMessageCredential with Windows client credentials and session establishment are used, allowing an observer to impersonate the authenticated Windows principal and decrypt or forge WS-SecureConversation traffic. This issue is fixed in version 1.9.1.
SeverityHigh
CVSS7.4
Exploit probability—
ProductCorewcf.primitives
PublishedJul 8, 2026
First seenJul 8, 2026
Weakness typeCWE-311CWE-311CWE-523CWE-523
How to fix
Update
- CoreWCF.Primitives1.9.1 or later
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| CoreWCF.PrimitivesNuGet | 1.9.0 ≤ v < 1.9.1 | 1.9.1 |
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