CVE-2026-49283: 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…

PriorityP351high8.7CVSS 3.1

AVNACLPRHUINSCCHIHAN

EPSS

0.47%

39.9th percentile

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.

Affected

8 ranges

Vendor	Product	Version range	Fixed in
simplesamlphp	saml2	< 4.19.3	4.19.3
simplesamlphp	saml2	—	—
simplesamlphp	saml2	—	—
simplesamlphp	saml2	—	—
simplesamlphp	saml2	>= 0 < 4.20.2	4.20.2
simplesamlphp	saml2	>= 5.0.0 < 5.0.6	5.0.6
simplesamlphp	saml2	>= 6.0.0 < 6.2.1	6.2.1
simplesamlphp	saml2-legacy	>= 0 < 4.20.2	4.20.2

Stop checking back — get the weekly exploitation signal.

Every Monday: what got weaponized or added to CISA KEV in the last seven days — each CVE cross-linked to its PoC, Nuclei template, and detection rule. Free, one email a week, unsubscribe in one click.