As per OASIS/SAML spec recommendation, If the message is signed, the Destination XML attribute in the root SAML element of the protocol message MUST contain the URL to which the sender has instructed the user agent to deliver the message. The recipient MUST then verify that the value matches the location at which the message has been received.

However, in keycloak, always validate the 'Destination'  on saml response. irrespective of response is signed or not.

is not a defect?

Arul kumar P.