CVE-2026-54773: CoreWCF WS-Security Signature Substitution Vulnerability

MODERATE
Advisory Identifier: GHSA-jc6x-rj79-w4mx
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CVSS 5.9
CWE-347
Published
Advisory Summary

CVE-2026-54773 is a MODERATE (CVSS 5.9) ws-security signature substitution vulnerability (CWE-347: Improper Verification of Cryptographic Signature) affecting CoreWCF libraries in the NuGet ecosystem. The issue involves ws-security signature substitution via document-wide signature lookup. Remediation is available by upgrading affected packages to version 1.8.1, 1.9.1.

CVE-2026-54773 at a Glance

CVE Identifier CVE-2026-54773
GHSA Identifier GHSA-jc6x-rj79-w4mx
Severity MODERATE
CVSS v3.1 Base Score 5.9
CWE Classification CWE-347: Improper Verification of Cryptographic Signature
Affected Product CoreWCF
Package Ecosystem NuGet
Published Date
Last Updated

Security Impact

CVSS: 5.9

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:N/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 None (C:N)
Integrity High (I:H)
Availability None (A:N)

How to Fix CVE-2026-54773

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: 1.8.1 
Upgrade CoreWCF.Primitives to 1.8.1
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-2026-54773, 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 1.8.1), 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-347: Improper Verification of Cryptographic Signature, where the product does not verify, or incorrectly verifies, the cryptographic signature for data. 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 An unauthenticated remote attacker who can place a SOAP header lexically before `wsse:Security` can embed a `ds:Signature` of their choosing inside that header and cause the server to verify the attacker-supplied signature instead of the one carried in the security header. #### Preconditions Exploitation requires the endpoint be configured with an endorsing supporting token binding, and the attacker constructs a `ds:Signature` whose `KeyInfo` resolves through the receive-side token resolver to a key under the attacker’s control. Both are conditions outside the attacker’s direct control on a generic deployment. ### Patches Fixed in CoreWCF v1.8.1 and v1.9.1 ### Workarounds Use a security token resolver that only accepts references to issuer-pinned X.509 chains (the default when expecting a static set of signing certificates).

CVE-2026-54773 Affected CoreWCF Versions

2 component(s)
Fixed Versions:
1.8.11.9.1
Product / Package Ecosystem Affected Versions Fixed Version
CoreWCF.Primitives
nuget/CoreWCF.Primitives
NuGet
< 1.8.1
1.8.1
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-jc6x-rj79-w4mx
CoreWCF Source Repository REPOSITORY
https://github.com/CoreWCF/CoreWCF

Frequently Asked Questions

What is CVE-2026-54773?
CVE-2026-54773 is a security vulnerability in CoreWCF involving WS-Security signature substitution via document-wide Signature lookup under CWE-347: Improper Verification of Cryptographic Signature.
Which CoreWCF versions are affected?
Affected versions include releases prior to 1.8.1, 1.9.1 across affected packages: CoreWCF.Primitives.
What version fixes CVE-2026-54773?
Upgrading to 1.8.1, 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 1.8.1, 1.9.1. Upgrade your dependency to 1.8.1, 1.9.1 or later.
What is the CVSS score of CVE-2026-54773?
CVE-2026-54773 has a CVSS v3.1 base score of 5.9 (MODERATE) with vector string CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N.
What CWE is associated with CVE-2026-54773?
CVE-2026-54773 is classified under CWE-347: Improper Verification of Cryptographic Signature (The product does not verify, or incorrectly verifies, the cryptographic signature for data.).
How can I check NuGet dependencies for CVE-2026-54773?
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-jc6x-rj79-w4mx",
  "modified" : "2026-06-19T20:46:43Z",
  "published" : "2026-06-19T20:46:43Z",
  "aliases" : [ "CVE-2026-54773" ],
  "summary" : "CoreWCF: WS-Security signature substitution via document-wide Signature lookup",
  "details" : "### Impact\nAn unauthenticated remote attacker who can place a SOAP header lexically before `wsse:Security` can embed a `ds:Signature` of their choosing inside that header and cause the server to verify the attacker-supplied signature instead of the one carried in the security header.\n\n#### Preconditions\nExploitation requires the endpoint be configured with an endorsing supporting token binding, and the attacker constructs a `ds:Signature` whose `KeyInfo` resolves through the receive-side token resolver to a key under the attacker’s control. Both are conditions outside the attacker’s direct control on a generic deployment.\n\n### Patches\nFixed in CoreWCF v1.8.1 and v1.9.1\n\n### Workarounds\nUse a security token resolver that only accepts references to issuer-pinned X.509 chains (the default when expecting a static set of signing certificates).",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "NuGet",
      "name" : "CoreWCF.Primitives"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "1.8.1"
      } ]
    } ]
  }, {
    "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-jc6x-rj79-w4mx"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/CoreWCF/CoreWCF"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-347" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-06-19T20:46:43Z",
    "nvd_published_at" : null
  }
}