A flaw was found in Keycloak. This issue allows an attacker, who controls another path on the same web server, to bypass the allowed path in redirect Uniform Resource Identifiers (URIs) that use a wildcard. A successful attack may lead to the theft of an access token, resulting in information disclosure.
To mitigate this vulnerability, avoid using wildcards in redirect_uri configurations within Keycloak. Restricting redirect_uri to explicit, fully qualified URIs prevents the bypass of validation logic. This configuration change may require a service restart or reload to take effect.