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Critical

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

  • Disclosed: 19.06.2026
  • Updated: 11.10.2026 11:23

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

Affected software

Click a technology to see all vulnerabilities affecting it.

PlatformPackageVulnerable versionsFixed in
.NET (NuGet) CoreWCF.Primitives < 1.8.1, >= 1.9.0, < 1.9.1 1.8.1, 1.9.1

References

CVSS score 10/10
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N
Weakness (CWE)
CWE-290, CWE-347
Platform
.NET (NuGet)
Package
CoreWCF.Primitives
Disclosed
19.06.2026
Updated
11.10.2026 11:23

Sources and licenses

OSV / GitHub Advisory Database - GHSA-xjr9-gg9q-jx3v - CC BY 4.0

Vulnerability history: CoreWCF.Primitives

All published vulnerabilities of this package (.NET (NuGet)), newest first. Shows whether this is a one-off slip or a package that needs watching.

Total entries
8
First → latest
06.2026 06.2026
Without a fix
0
Exploited in attacks
0

Severity breakdown

  • Critical 1
  • High 4
  • Medium 2
  • Low 1

Disclosures per year

  1. CoreWCF: SPNEGO SecurityContextToken proof key wrapped without confidentiality
    High · 7.4 CVE-2026-54784 >= 1.9.0, < 1.9.1 1.9.1
  2. CoreWCF: XML Signature Wrapping in WS-Security endorsing/supporting signature verification allows replay of captured signed messages
    High · 7.4 CVE-2026-54783 < 1.8.1, >= 1.9.0, < 1.9.1 1.8.1, 1.9.1
  3. CoreWCF: Authentication bypass in CoreWCF SAML 1.1 / 2.0 token signature validation this entry
    Critical · 10.0 CVE-2026-54782 < 1.8.1, >= 1.9.0, < 1.9.1 1.8.1, 1.9.1
  4. CoreWCF: SAML SubjectConfirmation methods and holder-of-key proof keys are not enforced
    High · 7.4 CVE-2026-54781 < 1.8.1, >= 1.9.0, < 1.9.1 1.8.1, 1.9.1
  5. CoreWCF: WS-Security Reference DigestMethod Algorithm-Suite Bypass
    Low · 3.7 CVE-2026-54780 < 1.8.1, >= 1.9.0, < 1.9.1 1.8.1, 1.9.1
  6. CoreWCF: SAML token replay protection is inoperative
    Medium · 5.9 CVE-2026-54779 < 1.8.1, >= 1.9.0, < 1.9.1 1.8.1, 1.9.1
  7. CoreWCF: SamlSerializer skips SignatureValue verification when SAML signing token is not an X.509 certificate
    High · 7.4 CVE-2026-54774 < 1.8.1, >= 1.9.0, < 1.9.1 1.8.1, 1.9.1
  8. CoreWCF: WS-Security signature substitution via document-wide Signature lookup
    Medium · 5.9 CVE-2026-54773 < 1.8.1, >= 1.9.0, < 1.9.1 1.8.1, 1.9.1

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