Selection of Less-Secure Algorithm During Negotiation ('Algorithm Downgrade') Affecting corewcf.primitives package, versions [,1.8.1)[1.9.0,1.9.1)
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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- published21 Jun 2026
- disclosed19 Jun 2026
- creditUnknown
Introduced: 19 Jun 2026
CVE-2026-54780 (opens in a new tab)How to fix?
Upgrade CoreWCF.Primitives to version 1.8.1, 1.9.1 or higher.
Overview
CoreWCF.Primitives is a port of the service side of Windows Communication Foundation (WCF) to .NET Core. The goal of this project is to enable existing WCF services to move to .NET Core.
Affected versions of this package are vulnerable to Selection of Less-Secure Algorithm During Negotiation ('Algorithm Downgrade') through the WSSecurityOneDotZeroReceiveSecurityHeader.VerifySignatureAsync path in CoreWCF.Security. An attacker can get a signed SOAP message accepted by supplying a ds:Reference DigestMethod URI that the configured SecurityAlgorithmSuite does not support. This lets a sender use a digest algorithm outside the suite’s advertised policy, causing the receiver to trust and process a signature that should have been rejected.