CVE-2026-49284 SimpleSAMLphp SP accepts a response from an unexpected IdP when unsigned `Response/InResponseTo` is combined with a signed assertion lacking `SubjectConfirmationData/InResponseTo`

SimpleSAMLphp versions before 1.18.6 contain an information disclosure vulnerability. Prior to 2.4.7 and 2.5.2, SimpleSAMLphp's SAML SP ACS path does not enforce the IdP selected for an SP-initiated login when unsigned Response/InResponseTo is combined with a signed assertion lacking...

CVE-2026-49284

The CVE affects SimpleSAMLphp SP: the ACS path permits a response from an unexpected IdP when an unsigned Response/InResponseTo combines with a signed assertion lacking SubjectConfirmationData/InResponseTo. A response from IdP B can be bound to SP state created for IdP A, allowing bypass of IdP-s...

CVE-2026-49284 SimpleSAMLphp SP accepts a response from an unexpected IdP when unsigned `Response/InResponseTo` is combined with a signed assertion lacking `SubjectConfirmationData/InResponseTo`

SimpleSAMLphp versions before 1.18.6 contain an information disclosure vulnerability. Prior to 2.4.7 and 2.5.2, SimpleSAMLphp's SAML SP ACS path does not enforce the IdP selected for an SP-initiated login when unsigned Response/InResponseTo is combined with a signed assertion lacking...

CVE-2026-54781

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 token validation does not enforce SubjectConfirmation method URIs or holder-of-key proof keys in SamlSecurityTokenHandler, allowing holder-of-key downgrade or custom...

CVE-2026-54781

CoreWCF (SAML token validation) does not enforce SubjectConfirmation method URIs or holder-of-key proof keys in SamlSecurityTokenHandler, allowing holder-of-key downgrade or custom confirmation method assertions to authenticate subjects without proper authority. Affects CoreWCF.Primitives and rel...

CVE-2026-54781

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 token validation does not enforce SubjectConfirmation method URIs or holder-of-key proof keys in SamlSecurityTokenHandler, allowing holder-of-key downgrade or custom...

CVE-2026-54781 CoreWCF: SAML SubjectConfirmation methods and holder-of-key proof keys are not enforced

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 token validation does not enforce SubjectConfirmation method URIs or holder-of-key proof keys in SamlSecurityTokenHandler, allowing holder-of-key downgrade or custom...

SimpleSAMLphp SP accepts a response from an unexpected IdP when unsigned `Response/InResponseTo` is combined with a signed assertion lacking `SubjectConfirmationData/InResponseTo`

Summary SimpleSAMLphp's SAML SP ACS path does not enforce the IdP selected for an SP-initiated login. If a saved SP state contains ExpectedIssuer = IdP A, but the ACS receives a valid response from IdP B, the code logs a warning and continues processing instead of rejecting the response. That...

Insufficient Verification of Data Authenticity

Overview simplesamlphp/simplesamlphp is a PHP implementation of a SAML 2.0 service provider and identity provider, also compatible with Shibboleth 1.3 and 2.0. Affected versions of this package are vulnerable to Insufficient Verification of Data Authenticity in the processing of SAML responses wh...

CoreWCF: SAML SubjectConfirmation methods and holder-of-key proof keys are not enforced

Impact The relying application is given a ClaimsPrincipal for a subject whose authority over the assertion the sender never proved. There are two distinct exploit shapes: - Holder-of-key downgrade. An attacker who obtains a holder-of-key SAML assertion that was issued without KeyInfo issuer bug,...

GHSA-63V5-26VQ-M4VM Keycloak's missing timestamp validation allows attackers to extend SAML response validity periods

A flaw was found in Keycloak's SAML brokering functionality. When Keycloak is configured as a client in a Security Assertion Markup Language SAML setup, it fails to validate the NotOnOrAfter timestamp within the SubjectConfirmationData. This allows an attacker to delay the expiration of SAML...

EUVD-2026-4670

A flaw was found in Keycloak's SAML brokering functionality. When Keycloak is configured as a client in a Security Assertion Markup Language SAML setup, it fails to validate the NotOnOrAfter timestamp within the SubjectConfirmationData. This allows an attacker to delay the expiration of SAML...

Subject Confirmation Method not validated in Saml2 Authentication Services for ASP.NET

Impact Saml2 tokens are usually used as bearer tokens - a caller that presents a token is assumed to be the subject of the token. There is also support in the Saml2 protocol for issuing tokens that is tied to a subject through other means, e.g. holder-of-key where possession of a private key must...

CVE-2020-5268

In Saml2 Authentication Services for ASP.NET versions before 1.0.2, and between 2.0.0 and 2.6.0, there is a vulnerability in how tokens are validated in some cases. Saml2 tokens are usually used as bearer tokens - a caller that presents a token is assumed to be the subject of the token. There is...

Session fixation

In Saml2 Authentication Services for ASP.NET versions before 1.0.2, and between 2.0.0 and 2.6.0, there is a vulnerability in how tokens are validated in some cases. Saml2 tokens are usually used as bearer tokens - a caller that presents a token is assumed to be the subject of the token. There is...

CVE-2020-5268

In Saml2 Authentication Services for ASP.NET, versions before 1.0.2 and between 2.0.0 and 2.6.0 contain a vulnerability in token validation. Sustainsys.Saml2 incorrectly treats all incoming tokens as bearer tokens, despite tokens being subject-confirmed by other means (e.g., holder-of-key). An at...

CVE-2020-5268 Subject Confirmation Method not validated in Saml2 Authentication Services for ASP.NET

In Saml2 Authentication Services for ASP.NET versions before 1.0.2, and between 2.0.0 and 2.6.0, there is a vulnerability in how tokens are validated in some cases. Saml2 tokens are usually used as bearer tokens - a caller that presents a token is assumed to be the subject of the token. There is...

CXF: Improper security semantics enforcement of SAML SubjectConfirmation methods

It was found that Apache WSS4J Web Services Security for Java, as used by Apache CXF with the TransportBinding, did not, by default, properly enforce all security requirements associated with SAML SubjectConfirmation methods. A remote attacker could use this flaw to perform various types of...

CXF: Improper security semantics enforcement of SAML SubjectConfirmation methods

It was found that Apache WSS4J Web Services Security for Java, as used by Apache CXF with the TransportBinding, did not, by default, properly enforce all security requirements associated with SAML SubjectConfirmation methods. A remote attacker could use this flaw to perform various types of...

CXF: Improper security semantics enforcement of SAML SubjectConfirmation methods

It was found that Apache WSS4J Web Services Security for Java, as used by Apache CXF with the TransportBinding, did not, by default, properly enforce all security requirements associated with SAML SubjectConfirmation methods. A remote attacker could use this flaw to perform various types of...