{"apiVersion":"1.0","identifier":"CVE-2026-49283","description":"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() attaches a TLS-based validator to the outer SOAP ArtifactResponse, while the embedded Response receives a validator that delegates to the outer message and is later checked against metadata selected from the embedded response issuer rather than necessarily the artifact issuer. SOAPClient::validateSSL() returns normally when the TLS public key does not match the key being validated, and SAML2\\Message::validate() treats a validator call that does not throw as successful. In a multi-IdP federation, a malicious or lower-trust IdP can therefore provide an ArtifactResponse containing an unsigned Response that claims a higher-trust victim IdP as issuer and authenticate as arbitrary users with attacker-chosen assertion attributes, NameID, and session data. This issue is fixed in versions 4.19.3, 4.20.2, 5.0.6, and 6.2.1.","publishedAt":"2026-08-19T15:17:07","lastModifiedAt":"2026-08-19T19:17:17","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-49283","cvssScore":8.7,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:N","epssProbability":0.00344,"riskScore":0.9,"affectedProduct":"SimpleSAMLphp","affectedVersions":"<4.19.3, <4.20.2, <5.0.6, <6.2.1","vulnerabilityType":"Library","operatingSystems":[],"links":{"self":"https://www.redsauce.net/api/cves/CVE-2026-49283","webPages":{"es":"https://www.redsauce.net/es/cves/CVE-2026-49283","en":"https://www.redsauce.net/en/cves/CVE-2026-49283","fr":"https://www.redsauce.net/fr/cves/CVE-2026-49283","pt":"https://www.redsauce.net/pt/cves/CVE-2026-49283","de":"https://www.redsauce.net/de/cves/CVE-2026-49283","sk":"https://www.redsauce.net/sk/cves/CVE-2026-49283","el":"https://www.redsauce.net/el/cves/CVE-2026-49283"},"source":"https://nvd.nist.gov/vuln/detail/CVE-2026-49283"}}