A flaw was found in Keycloak. This issue may allow an attacker to steal authorization codes or tokens from clients using a wildcard in the JARM response mode "form_post.jwt" which could be used to bypass the security patch implemented to address CVE-2023-6134.
Credits
Red Hat would like to thank Pontus Hanssen (Pontus.Hanssen@omegapoint.se) for reporting this issue.