CVE-2026-54780: CoreWCF WS-Security Reference DigestMethod Algorithm-Suite Bypass Vulnerability

LOW
Advisory Identifier: GHSA-4v55-cpmv-3vcm
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CVSS 3.7
CWE-757 CWE-327
Published
Advisory Summary

CVE-2026-54780 is a LOW (CVSS 3.7) ws-security reference digestmethod algorithm-suite bypass vulnerability (CWE-757: Selection of Less-Secure Algorithm During Negotiation ('Algorithm Downgrade')) affecting CoreWCF libraries in the NuGet ecosystem. The issue involves ws-security reference digestmethod algorithm-suite bypass. Remediation is available by upgrading affected packages to version 1.8.1, 1.9.1.

CVE-2026-54780 at a Glance

CVE Identifier CVE-2026-54780
GHSA Identifier GHSA-4v55-cpmv-3vcm
Severity LOW
CVSS v3.1 Base Score 3.7
CWE Classification CWE-757: Selection of Less-Secure Algorithm During Negotiation ('Algorithm Downgrade')
Affected Product CoreWCF
Package Ecosystem NuGet
Published Date
Last Updated

Security Impact

CVSS: 3.7

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:L/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 Low (I:L)
Availability None (A:N)

How to Fix CVE-2026-54780

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-2026-54780, 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-757: Selection of Less-Secure Algorithm During Negotiation ('Algorithm Downgrade'), where a protocol or its implementation supports interaction between multiple actors and allows those actors to negotiate which algorithm should be used as a protection mechanism such as encryption or authentication, but it does not select the strongest algorithm that is available to both parties. 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 CoreWCF’s WS-Security 1.0 receive pipeline validates the `SignatureMethod` of an incoming `ds:SignedInfo` against the configured `SecurityAlgorithmSuite`, but does not validate the `DigestMethod` declared on each `ds:Reference`. As a result, a sender can populate `ds:SignedInfo` with `SignatureMethod` values the suite accepts (for example rsa-sha256 under Basic256Sha256) while declaring a per-reference `DigestMethod` the suite rejects (for example http://www.w3.org/2000/09/xmldsig#sha1). The signature is then verified where it permits SHA-1 digests, and the message is accepted. ### Patches Fixed in CoreWCF v1.8.1 and v1.9.1 ### Workarounds None

CVE-2026-54780 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-4v55-cpmv-3vcm
CoreWCF Source Repository REPOSITORY
https://github.com/CoreWCF/CoreWCF

Frequently Asked Questions

What is CVE-2026-54780?
CVE-2026-54780 is a security vulnerability in CoreWCF involving WS-Security Reference DigestMethod Algorithm-Suite Bypass under CWE-757: Selection of Less-Secure Algorithm During Negotiation ('Algorithm Downgrade').
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-2026-54780?
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-2026-54780?
CVE-2026-54780 has a CVSS v3.1 base score of 3.7 (LOW) with vector string CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N.
What CWE is associated with CVE-2026-54780?
CVE-2026-54780 is classified under CWE-757: Selection of Less-Secure Algorithm During Negotiation ('Algorithm Downgrade') (A protocol or its implementation supports interaction between multiple actors and allows those actors to negotiate which algorithm should be used as a protection mechanism such as encryption or authentication, but it does not select the strongest algorithm that is available to both parties.).
How can I check NuGet dependencies for CVE-2026-54780?
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-4v55-cpmv-3vcm",
  "modified" : "2026-06-19T20:47:04Z",
  "published" : "2026-06-19T20:47:04Z",
  "aliases" : [ "CVE-2026-54780" ],
  "summary" : "CoreWCF: WS-Security Reference DigestMethod Algorithm-Suite Bypass",
  "details" : "### Impact\nCoreWCF’s WS-Security 1.0 receive pipeline validates the `SignatureMethod` of an incoming `ds:SignedInfo` against the configured `SecurityAlgorithmSuite`, but does not validate the `DigestMethod` declared on each `ds:Reference`. As a result, a sender can populate `ds:SignedInfo` with `SignatureMethod` values the suite accepts (for example rsa-sha256 under Basic256Sha256) while declaring a per-reference `DigestMethod` the suite rejects (for example http://www.w3.org/2000/09/xmldsig#sha1). The signature is then verified where it permits SHA-1 digests, and the message is accepted.\n\n### Patches\nFixed in CoreWCF v1.8.1 and v1.9.1\n\n### Workarounds\nNone",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/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-4v55-cpmv-3vcm"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/CoreWCF/CoreWCF"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-327", "CWE-757" ],
    "severity" : "LOW",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-06-19T20:47:04Z",
    "nvd_published_at" : null
  }
}