The vulnerability exists in the org.keycloak.protocol.oidc.utils.RedirectUtils class. Specifically, the private method areWildcardsAllowed had insufficient validation for redirect URIs. When a URI with multiple '@' characters in the user-info part (e.g., https://test@something@test.com) is passed, the Java URI class fails to parse the user-info, host, and port correctly, but leaves the raw authority field populated. The original implementation of areWildcardsAllowed only checked if getRawUserInfo() returned null. For the malicious input, it did, causing the function to incorrectly return true, allowing a wildcard redirect. The public method verifyRedirectUri calls areWildcardsAllowed and is the function that would appear in a runtime profile when the vulnerability is triggered. The patch introduced an additional check in areWildcardsAllowed to verify that if the raw authority is present, the user-info, host, and port are also parsed, thus preventing the bypass.