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

When processing authorization requests using the whitelabel views in Spring Security OAuth 2.0.0 to 2.0.9 and 1.0.0 to 1.0.5, the responsetype parameter value was executed as Spring SpEL which enabled a malicious user to trigger remote code execution via the crafting of the value for responsetype.