Keycloak 26.6.3 released

Keycloak 26.6.3 is a patch release that addresses 16 security vulnerabilities spanning OIDC token handling, CORS misconfigurations, server-side request forgery, improper access controls, and WebAuthn validation gaps. Beyond security fixes, the update resolves 31 bugs and includes 4 enhancements, most notably an upgrade to Quarkus 3.33.2 and startup checks for missing database indexes. Additional fixes target LDAP federation, realm migrations, and privilege escalation through token exchange mechanisms.