# CVE-2026-54773: CoreWCF improper signature verification in WS-Security

Source: https://junglewise.ai/threats/cve-2026-54773-corewcf-improper-signature-verification-in-ws-security  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-07-08. Updated: 2026-07-08  
License: CC BY 4.0 with a link back

CVE-2026-54773 · Severity: medium · CVSS 5.9 · Published 2026-07-08

CoreWCF is a library used to build web services in .NET applications. A security flaw in how it verifies digital signatures could allow an attacker to bypass security checks by providing their own signature in a specially crafted message. This could lead to the service accepting unauthorized or tampered data as if it were legitimate.

Technologies: [CoreWCF](https://junglewise.ai/threats/technologies/corewcf), [CoreWCF.Primitives (NuGet)](https://junglewise.ai/threats/technologies/corewcf-primitives). Vendors: [CoreWCF](https://junglewise.ai/threats/vendors/corewcf), [NuGet](https://junglewise.ai/threats/vendors/nuget).

## Quick answers

**Is CVE-2026-54773 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-54773 being exploited in the wild.

**How severe is CVE-2026-54773?** Medium severity, with a CVSS score of 5.9, published 8 July 2026.

**Which products and versions are affected?** CoreWCF < 1.8.1, >= 1.9.0 < 1.9.1; CoreWCF.Primitives (NuGet) ECOSYSTEM:introduced=0,fixed=1.8.1.

**Is there a fix for CVE-2026-54773?** Yes. CoreWCF.Primitives (NuGet): upgrade to 1.8.1 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-54773 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-54773?** Check whether you run CoreWCF or CoreWCF.Primitives (NuGet) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- CoreWCF.Primitives (NuGet): upgrade to 1.8.1 or later

  ```sh
  dotnet add package CoreWCF.Primitives --version 1.8.1
  ```


## Technical details

A signature verification vulnerability exists in CoreWCF's WS-Security implementation. The 'WSSecurityOneDotZeroReceiveSecurityHeader' component performs a document-wide 'ds:Signature' lookup rather than restricting the search to the 'wsse:Security' header. An unauthenticated remote attacker can exploit this by placing a SOAP header before the security header, causing the system to verify an attacker-controlled signature instead of the intended one. This is classified as improper verification of cryptographic signatures (CWE-347). The issue is resolved in versions 1.8.1 and 1.9.1 by binding the signature lookup specifically to the Security header subtree.

## Affected products

- CoreWCF CoreWCF < 1.8.1, >= 1.9.0 < 1.9.1

## Identifiers

- CVE-2026-54773
- GHSA-jc6x-rj79-w4mx

## Timeline

- 2026-07-08: advisory: NVD publication date
- 2026-07-08: disclosed: GitHub Security Advisory published
- 2026-06-16: patched: Fix committed to repository

## References

- [https://github.com/CoreWCF/CoreWCF/commit/0589692d4b9a41d21b34ac48281e95f6df7f4ce5](https://github.com/CoreWCF/CoreWCF/commit/0589692d4b9a41d21b34ac48281e95f6df7f4ce5)
- [https://github.com/CoreWCF/CoreWCF/commit/30aef805270976c42477e3f2a05f4e563d86e247](https://github.com/CoreWCF/CoreWCF/commit/30aef805270976c42477e3f2a05f4e563d86e247)
- [https://github.com/CoreWCF/CoreWCF/commit/4618f24165ad018ad3ed2636bf8c3bc87d2a3be2](https://github.com/CoreWCF/CoreWCF/commit/4618f24165ad018ad3ed2636bf8c3bc87d2a3be2)
- [https://github.com/CoreWCF/CoreWCF/releases/tag/v1.8.1](https://github.com/CoreWCF/CoreWCF/releases/tag/v1.8.1)
- [https://github.com/CoreWCF/CoreWCF/releases/tag/v1.9.1](https://github.com/CoreWCF/CoreWCF/releases/tag/v1.9.1)
- [https://github.com/CoreWCF/CoreWCF/security/advisories/GHSA-jc6x-rj79-w4mx](https://github.com/CoreWCF/CoreWCF/security/advisories/GHSA-jc6x-rj79-w4mx)

## Related threats

- [CoreWCF cleartext proof key exposure in SPNEGO negotiation](https://junglewise.ai/threats/cve-2026-54784-corewcf-cleartext-proof-key-exposure-in-spnego-negotiation)
- [CoreWCF signature verification bypass in WS-Security](https://junglewise.ai/threats/cve-2026-54783-corewcf-signature-verification-bypass-in-ws-security)
- [CoreWCF authentication bypass in SAML token validation](https://junglewise.ai/threats/cve-2026-54782-corewcf-authentication-bypass-in-saml-token-validation)
- [CoreWCF improper authentication in SAML SamlSecurityTokenHandler](https://junglewise.ai/threats/cve-2026-54781-corewcf-improper-authentication-in-saml-samlsecuritytokenhandler)
- [CoreWCF algorithm downgrade in WS-Security receive pipeline](https://junglewise.ai/threats/cve-2026-54780-corewcf-algorithm-downgrade-in-ws-security-receive-pipeline)