CVE-2026-54782 in CoreWCF
Summary
by MITRE • 07/09/2026
CoreWCF is a port of the service side of Windows Communication Foundation (WCF) to .NET Core. Prior to 1.8.1 and 1.9.1, CoreWCF SAML 1.1 and SAML 2.0 token validation does not correctly resolve the issuer signing key or require signed tokens when IdentityConfiguration is used with federated bindings, allowing an unauthenticated remote attacker to impersonate any principal the trusted STS could issue. This issue is fixed in versions 1.8.1 and 1.9.1.
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Analysis
by VulDB Data Team • 07/09/2026
CoreWCF represents a significant evolution in .NET communication frameworks, providing developers with a robust service-oriented architecture implementation that bridges the gap between traditional Windows Communication Foundation and modern cross-platform development environments. The vulnerability under analysis affects the authentication and authorization mechanisms within CoreWCF's security infrastructure, specifically targeting the SAML token validation process that serves as a critical component for federated identity management in distributed applications. This flaw exists in versions prior to 1.8.1 and 1.9.1, creating a substantial security risk that undermines the fundamental trust model of federated authentication systems.
The technical root cause of this vulnerability lies in the improper handling of issuer signing key resolution during SAML token validation processes. When IdentityConfiguration is utilized with federated bindings, the system fails to correctly validate the cryptographic signatures associated with SAML tokens, particularly those conforming to versions 1.1 and 2.0. This cryptographic weakness stems from insufficient verification of token authenticity and inadequate key management practices within the token processing pipeline. The flaw manifests when the system does not properly enforce signature validation requirements, allowing malformed or unsigned tokens to be accepted as legitimate authentication artifacts. This represents a direct violation of security principle 377, which mandates proper cryptographic validation of all security tokens in identity systems.
The operational impact of this vulnerability extends far beyond simple authentication bypass scenarios, creating a comprehensive compromise of the federated identity infrastructure. An unauthenticated remote attacker can exploit this weakness to impersonate any principal that the trusted Security Token Service could legitimately issue, effectively granting them unlimited access to resources protected by the compromised CoreWCF service. This attack vector aligns with attack technique T1566 in the MITRE ATT&CK framework, specifically targeting credential manipulation through authentication token exploitation. The implications are particularly severe in enterprise environments where CoreWCF services often handle sensitive data and critical business operations, as the attacker can essentially assume any identity within the trusted federation domain.
The vulnerability demonstrates a clear failure in cryptographic security implementation that directly impacts the integrity and authenticity guarantees of the federated authentication system. Organizations relying on CoreWCF for secure service communication face significant risk exposure, as this flaw allows attackers to forge authentication tokens without requiring legitimate credentials or access to private keys. The attack scenario becomes particularly dangerous when considering that SAML tokens are commonly used in enterprise Single Sign-On (SSO) implementations and cloud-based identity federation scenarios where trust relationships between multiple security domains are established. This weakness creates a pathway for privilege escalation attacks and lateral movement within networks where CoreWCF services are deployed, as authenticated access to one service can potentially lead to access to other systems within the federated trust boundary.
Security mitigations for this vulnerability require immediate deployment of patches to versions 1.8.1 and 1.9.1, which address the fundamental cryptographic validation issues in the token processing pipeline. Organizations should implement comprehensive monitoring of authentication events and token validation failures to detect potential exploitation attempts. Additionally, security teams must review existing trust relationships and certificate management practices to ensure that proper key rotation and validation procedures are maintained. The remediation process should include thorough testing of federated authentication flows to verify that signature validation is properly enforced and that the system correctly resolves issuer signing keys for all supported SAML versions. This vulnerability serves as a critical reminder of the importance of maintaining up-to-date security implementations in distributed systems, particularly those handling identity and access management functions.