An incomplete fix was found in Keycloak Core patch. An attacker can steal authorization codes or tokens from clients using a wildcard in the JARM response mode "form_post.jwt". It is observed that changing the response_mode parameter in the original proof of concept from "form_post" to "form_post.jwt" can bypass the security patch implemented to address CVE-2023-6134.
23.0.4Exploitability
AV:NAC:LPR:LUI:RScope
S:UImpact
C:LI:LA:N4.6/CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:L/A:N