Jenkins SAML Plugin 4.583.vc68232f7018a_ and earlier does not implement a replay cache, allowing attackers able to obtain information about the SAML authentication flow between a users web browser and Jenkins to replay those requests, authenticating to Jenkins as that user.
A capture-replay flaw exists when the design of the product makes it possible for a malicious user to sniff network traffic and bypass authentication by replaying it to the server in question to the same effect as the original message (or with minor changes).