A flaw was found in the User-Managed Access (UMA) implementation of Keycloak. The issue occurs in the authorization token endpoint when processing permission tickets. If two different users own resources with the same name, the system incorrectly merges the permissions from both resources when one user requests an authorization token. This allows an attacker to gain access scopes on a victim's resource that were never intended to be shared.
Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.