SimpleSAMLphp up to 4.19.2/4.20.1/5.0.5/6.2.0 SAML2 Library HTTPArtifact::receive data authenticity

Summaryinfo

A vulnerability was found in SimpleSAMLphp up to 4.19.2/4.20.1/5.0.5/6.2.0 and classified as problematic. The affected element is the function HTTPArtifact::receive of the component SAML2 Library. Executing a manipulation can lead to data authenticity. The identification of this vulnerability is CVE-2026-49283. The attack may be launched remotely. There is no exploit available.

Detailsinfo

A vulnerability has been found in SimpleSAMLphp up to 4.19.2/4.20.1/5.0.5/6.2.0 and classified as problematic. This vulnerability affects the function HTTPArtifact::receive of the component SAML2 Library. The manipulation with an unknown input leads to a data authenticity vulnerability. The CWE definition for the vulnerability is CWE-345. The product does not sufficiently verify the origin or authenticity of data, in a way that causes it to accept invalid data. As an impact it is known to affect confidentiality, integrity, and availability. CVE summarizes:

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.

The advisory is shared for download at github.com. This vulnerability was named CVE-2026-49283 since 05/28/2026. The exploitation appears to be easy. The attack can be initiated remotely. Additional levels of successful authentication are needed for exploitation. There are known technical details, but no exploit is available.

Upgrading to version 4.19.3, 4.20.2, 5.0.6 or 6.2.1 eliminates this vulnerability.

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Productinfo

Name

• SimpleSAMLphp

Version

• 4.19.0
• 4.19.1
• 4.19.2
• 4.20.0
• 4.20.1
• 5.0.0
• 5.0.1
• 5.0.2
• 5.0.3
• 5.0.4
• 5.0.5
• 6.0
• 6.1
• 6.2.0

License

• open-source

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