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

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, CoreWCF.Primitives (NuGet). Vendors: CoreWCF, 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
    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

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