Spring Security OAuth, versions 2.3 prior to 2.3.4, and 2.2 prior to 2.2.3, and 2.1 prior to 2.1.3, and 2.0 prior to 2.0.16, and older unsupported versions could be susceptible to a privilege escalation under certain conditions. A malicious user or attacker can craft a request to the approval endpoint that can modify the previously saved authorization request and lead to a privilege escalation on the subsequent approval. This scenario can happen if the application is configured to use a custom approval endpoint that declares AuthorizationRequest as a controller method argument.

External References:

https://pivotal.io/security/cve-2018-15758

Spring Security OAuth could allow a remote attacker to conduct phishing attacks, caused by an open redirect vulnerability in authorization endpoint. An attacker could exploit this vulnerability using a specially-crafted URL to redirect a victim to arbitrary Web sites.