# CVE-2026-54780: CoreWCF algorithm downgrade in WS-Security receive pipeline

Source: https://junglewise.ai/threats/cve-2026-54780-corewcf-algorithm-downgrade-in-ws-security-receive-pipeline  
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-2026-54780 · Severity: low · CVSS 3.7 · Published 2026-07-08

CoreWCF is a library used to build web services on .NET Core. A security flaw in its message processing pipeline allows the system to accept digital signatures created with weak or rejected security algorithms, such as SHA-1. While this does not directly expose data, it could allow an attacker to bypass certain security policies intended to enforce modern cryptographic standards.

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-2026-54780 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-54780 being exploited in the wild.

**How severe is CVE-2026-54780?** Low severity, with a CVSS score of 3.7, 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-2026-54780?** 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-2026-54780 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-54780?** 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 vulnerability exists in the CoreWCF WS-Security 1.0 receive pipeline where the 'ds:Reference DigestMethod' is not validated against the configured 'SecurityAlgorithmSuite'. While the 'SignatureMethod' is correctly checked, the individual digest algorithms for message references are ignored during the policy enforcement phase. This allows a remote attacker to send messages using weak or deprecated digest algorithms (e.g., SHA-1) that should have been rejected by the service policy. The fix restores the 'EnsureAcceptableDigestAlgorithm' helper and ensures it is called for every reference in the 'SignedInfo' block during signature verification.

## Affected products

- CoreWCF CoreWCF < 1.8.1, >= 1.9.0 < 1.9.1

## Identifiers

- CVE-2026-54780
- GHSA-4v55-cpmv-3vcm

## Timeline

- 2026-07-08: advisory: NVD publication date
- 2026-07-08: disclosed: GitHub Security Advisory published

## References

- [https://github.com/CoreWCF/CoreWCF/commit/58742312117cc671e6e9c694c2f5f9f669c17136](https://github.com/CoreWCF/CoreWCF/commit/58742312117cc671e6e9c694c2f5f9f669c17136)
- [https://github.com/CoreWCF/CoreWCF/commit/9104e581cff3d047ace5e179bfae86807a44be1f](https://github.com/CoreWCF/CoreWCF/commit/9104e581cff3d047ace5e179bfae86807a44be1f)
- [https://github.com/CoreWCF/CoreWCF/commit/fea67b2cd73a5a85115c325d504303ec7382e133](https://github.com/CoreWCF/CoreWCF/commit/fea67b2cd73a5a85115c325d504303ec7382e133)
- [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-4v55-cpmv-3vcm](https://github.com/CoreWCF/CoreWCF/security/advisories/GHSA-4v55-cpmv-3vcm)

## 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 SAML token replay protection bypass in DefaultTokenReplayCache](https://junglewise.ai/threats/cve-2026-54779-corewcf-saml-token-replay-protection-bypass-in)