---
id: CVE-2026-54773
title: 'CoreWCF: WS-Security signature substitution via document-wide Signature lookup'
summary: 'CoreWCF: WS-Security signature substitution via document-wide Signature lookup'
severity: medium
cvss: 5.9
cwe:
  - CWE-347
vendor: CoreWCF
product: CoreWCF.Primitives
ecosystem: nuget
affected:
  - CoreWCF.Primitives < 1.8.1
  - 'CoreWCF.Primitives >= 1.9.0, < 1.9.1'
patched:
  - CoreWCF.Primitives 1.8.1
  - CoreWCF.Primitives 1.9.1
published: '2026-06-19'
updated: '2026-06-19'
source: GHSA
sourceUrl: 'https://github.com/advisories/GHSA-jc6x-rj79-w4mx'
references:
  - url: 'https://github.com/CoreWCF/CoreWCF/security/advisories/GHSA-jc6x-rj79-w4mx'
  - url: 'https://github.com/advisories/GHSA-jc6x-rj79-w4mx'
tags:
  - ghsa
  - nuget
ingestedAt: '2026-06-22T13:35:24.442Z'
epss: 0.0037
epssPercentile: 0.28178
---

## Overview

### 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).

## Affected packages

- `CoreWCF.Primitives < 1.8.1`
- `CoreWCF.Primitives >= 1.9.0, < 1.9.1`

## Remediation

Upgrade to a patched release:

- `CoreWCF.Primitives 1.8.1`
- `CoreWCF.Primitives 1.9.1`