CVE-2026-54784: CoreWCF SPNEGO SecurityContextToken Proof Key Wrapped Vulnerability

HIGH
Advisory Identifier: GHSA-2288-8h3r-cqgg
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CVSS 7.4
CWE-311 CWE-523
Published
Advisory Summary

CVE-2026-54784 is a HIGH (CVSS 7.4) spnego securitycontexttoken proof key wrapped vulnerability (CWE-311: Missing Encryption of Sensitive Data) affecting CoreWCF libraries in the NuGet ecosystem. The issue involves spnego securitycontexttoken proof key wrapped without confidentiality. Remediation is available by upgrading affected packages to version 1.9.1.

CVE-2026-54784 at a Glance

CVE Identifier CVE-2026-54784
GHSA Identifier GHSA-2288-8h3r-cqgg
Severity HIGH
CVSS v3.1 Base Score 7.4
CWE Classification CWE-311: Missing Encryption of Sensitive Data
Affected Product CoreWCF
Package Ecosystem NuGet
Published Date
Last Updated

Security Impact

CVSS: 7.4

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N).

Attack Vector Network (AV:N)
Attack Complexity High (AC:H)
Privileges Required None (PR:N)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality High (C:H)
Integrity High (I:H)
Availability None (A:N)

How to Fix CVE-2026-54784

To remediate this vulnerability, upgrade all affected CoreWCF dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

CoreWCF.Primitives fixed: 1.9.1 
Upgrade CoreWCF.Primitives to 1.9.1
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

inspect dependencies for CoreWCF.Primitives

How to Check if You Are Affected

To determine whether your application is affected by CVE-2026-54784, inspect your project dependencies for CoreWCF:

inspect dependencies for CoreWCF.Primitives

Analyze the terminal output to locate any version of CoreWCF in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 1.9.1), your application is affected.

Note: Verify declared build manifests and deployed runtime container environments.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-311: Missing Encryption of Sensitive Data, where the product does not encrypt sensitive or critical information before storage or transmission. In CoreWCF, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

### 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.

CVE-2026-54784 Affected CoreWCF Versions

1 component(s)
Fixed Versions:
1.9.1
Product / Package Ecosystem Affected Versions Fixed Version
CoreWCF.Primitives
nuget/CoreWCF.Primitives
NuGet
≥ 1.9.0
< 1.9.1
1.9.1

References

GitHub Advisory / Wiki ADVISORY
https://github.com/CoreWCF/CoreWCF/security/advisories/GHSA-2288-8h3r-cqgg
CoreWCF Source Repository REPOSITORY
https://github.com/CoreWCF/CoreWCF

Frequently Asked Questions

What is CVE-2026-54784?
CVE-2026-54784 is a security vulnerability in CoreWCF involving SPNEGO SecurityContextToken proof key wrapped without confidentiality under CWE-311: Missing Encryption of Sensitive Data.
Which CoreWCF versions are affected?
Affected versions include releases prior to 1.9.1 across affected packages: CoreWCF.Primitives.
What version fixes CVE-2026-54784?
Upgrading to 1.9.1 (or the latest patched release for your respective branch) resolves the vulnerability.
Is CoreWCF.Primitives affected?
Yes, CoreWCF.Primitives is affected in releases prior to 1.9.1. Upgrade your dependency to 1.9.1 or later.
What is the CVSS score of CVE-2026-54784?
CVE-2026-54784 has a CVSS v3.1 base score of 7.4 (HIGH) with vector string CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N.
What CWE is associated with CVE-2026-54784?
CVE-2026-54784 is classified under CWE-311: Missing Encryption of Sensitive Data (The product does not encrypt sensitive or critical information before storage or transmission.).
How can I check NuGet dependencies for CVE-2026-54784?
Run the dependency tree command: 'inspect dependencies for CoreWCF.Primitives'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-2288-8h3r-cqgg",
  "modified" : "2026-06-19T20:47:17Z",
  "published" : "2026-06-19T20:47:17Z",
  "aliases" : [ "CVE-2026-54784" ],
  "summary" : "CoreWCF: SPNEGO SecurityContextToken proof key wrapped without confidentiality",
  "details" : "### Impact\nWhen 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.\n\n#### Preconditions\nUsing security mode TransportWithMessageCredential with client credential type Windows, along with session establishment (which triggers use of WS-SecureConversation).\n\n### Patches\nFixed in CoreWCF v1.9.1\n\n### Workarounds\nEnsure communication is protected by SSL/TLS to prevent capturing of SCT negotiation handshake.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "NuGet",
      "name" : "CoreWCF.Primitives"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "1.9.0"
      }, {
        "fixed" : "1.9.1"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/CoreWCF/CoreWCF/security/advisories/GHSA-2288-8h3r-cqgg"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/CoreWCF/CoreWCF"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-311", "CWE-523" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-06-19T20:47:17Z",
    "nvd_published_at" : null
  }
}