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CVE-2026-54782 — CoreWCF: Authentication bypass in...

CRITICAL

CoreWCF: Authentication bypass in CoreWCF SAML 1.1 / 2.0 token signature validation

Published June 19, 2026Updated June 19, 2026Source: osv

Summary

### Impact Full impersonation of any principal the trusted STS could have issued an assertion for — including administrative principals when the relying party grants them via SAML claims. Affects both SAML 1.1 and SAML 2.0. #### Preconditions Relying-party service is hosted with WSFederationHttpBinding or WS2007FederationHttpBinding (or any binding that triggers FederatedSecurityTokenManager for issued-token validation), and IdentityConfiguration is wired (UseIdentityConfiguration = true). Attacker can reach the service over the network and knows the trusted STS’s public certificate (public certs are by design discoverable). ### Patches Fixed in CoreWCF v1.8.1 and v1.9.1 ### Workarounds None

Advisory Timeline

  • First published June 19, 2026 (115 days ago).
  • Last revised June 19, 2026 — 0 days after initial publication.

Remediation

Upgrade to the fixed version using your package manager.

NuGet
Update CoreWCF.Primitives to 1.8.1 or later
dotnet add package CoreWCF.Primitives --version 1.8.1
NuGet
Update CoreWCF.Primitives to 1.9.1 or later
dotnet add package CoreWCF.Primitives --version 1.9.1

After upgrading, run your dependency scanner again to confirm the vulnerability is resolved.

Affected Packages (2)

Affects 1 ecosystem: nuget (1).

PackageEcosystemAffectedFixed In
CoreWCF.Primitives
nuget
0.1.0, 0.1.0-preview, 0.1.0-preview-2, 0.2.0 (+28 more)1.8.1
CoreWCF.Primitives
nuget
1.9.01.9.1

Vulnerability Classification

Common Weakness Enumeration (CWE) identifiers for this vulnerability type.

CVSS Score Breakdown

What the CVSS (Common Vulnerability Scoring System) 10.0 score means for each attack dimension.

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Changed
Confidentiality
High
Integrity
High
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N

References

Frequently Asked Questions

What is CVE-2026-54782?
CoreWCF: Authentication bypass in CoreWCF SAML 1.1 / 2.0 token signature validation This vulnerability has been assigned a severity rating of CRITICAL (CVSS score: 10.0/10).
How do I check if my project is affected by CVE-2026-54782?
CVE-2026-54782 affects CoreWCF.Primitives. Use GeekWala's free vulnerability scanner to check your dependencies against CVE-2026-54782 and 200,000+ other known vulnerabilities.

Severity & Exploitability

CVSS Score
10.0

Exploitation is straightforward and causes maximum impact. Patch immediately.

Also Known As

GHSA-xjr9-gg9q-jx3v

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