Keycloak Open Redirect vulnerability

An open redirect vulnerability was found in Keycloak. A specially crafted URL can be constructed where the `referrer` and `referrer_uri` parameters are made to trick a user to visit a malicious webpage. A trusted URL can trick users and automation into believing that the URL is safe, when, in fact, it redirects to a malicious server. This issue can result in a victim inadvertently trusting the destination of the redirect, potentially leading to a successful phishing attack or other types of attacks. Once a crafted URL is made, it can be sent to a Keycloak admin via email for example. This will trigger this vulnerability when the user visits the page and clicks the link. A malicious actor can use this to target users they know are Keycloak admins for further attacks. It may also be possible to bypass other domain-related security checks, such as supplying this as a OAuth redirect uri. The malicious actor can further obfuscate the `redirect_uri` using URL encoding, to hide the text of the actual malicious website domain.

Quoted source text, attributed separately from HOL analysis.