CoreWCF: SPNEGO SecurityContextToken proof key wrapped without confidentiality
Impact
When the proof key recovered from the RSTR can be observed by a party that is not the legitimate client, that party can impersonate the authenticated Windows principal for the lifetime of the SCT (default ~10 hours) and decrypt or forge any subsequent WS‑SecureConversation traffic that uses keys derived from the SCT.
Preconditions
Using security mode TransportWithMessageCredential with client credential type Windows, along with session establishment (which triggers use of WS-SecureConversation).
Patches
Fixed in CoreWCF v1.9.1
Workarounds
Ensure communication is protected by SSL/TLS to prevent capturing of SCT negotiation handshake.
Affected software
Click a technology to see all vulnerabilities affecting it.
| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| .NET (NuGet) | CoreWCF.Primitives | >= 1.9.0, < 1.9.1 | 1.9.1 |
References
- CVSS vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N- Weakness (CWE)
CWE-311, CWE-523- Platform
- .NET (NuGet)
- Package
CoreWCF.Primitives- Disclosed
- 19.06.2026
- Updated
- 11.10.2026 11:23
Sources and licenses
OSV / GitHub Advisory Database - GHSA-2288-8h3r-cqgg - CC BY 4.0
Vulnerability history: CoreWCF.Primitives
All published vulnerabilities of this package (.NET (NuGet)), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 8
- First → latest
- 06.2026 06.2026
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- Critical 1
- High 4
- Medium 2
- Low 1
Disclosures per year
- 2026: 8
-
CoreWCF: SPNEGO SecurityContextToken proof key wrapped without confidentiality this entry
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