CVE-2026-49283 SimpleSAMLphp HTTP-Artifact TLS validator confusion allows cross-IdP authentication bypass

The SimpleSAMLphp SAML2 library is a PHP library for SAML2 related functionality. Prior to versions 4.19.3, 4.20.2, 5.0.6, and 6.2.1, the HTTPArtifact::receive flow can treat an unsigned embedded SAML Response as cryptographically valid for the wrong identity provider. SOAPClient::addSSLValidator...

GHSA-Q8R6-XJ3F-WRRM 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...

GHSA-6929-8P9F-26JX SimpleSAMLphp HTTP-Artifact TLS validator confusion allows cross-IdP authentication bypass

Summary SimpleSAMLphp's HTTP-Artifact receive path can treat an unsigned embedded SAML Response as cryptographically valid for the wrong IdP. In the HTTPArtifact::receive flow, the SOAP ArtifactResponse receives a TLS-based validator from SOAPClient::addSSLValidator. The embedded SAML Response th...