A flaw was found in Keycloak. When a JSON Web Encryption (JWE) encrypted request object is submitted, Keycloak may incorrectly process unsigned claims if the decrypted content is raw JSON, bypassing the configured signature policy. This allows a remote attacker to submit unauthorized claims, leading to a compromise of data integrity within the OpenID Connect (OIDC) authorization flow. While a redirect URI allowlist acts as a compensating control, this vulnerability violates OIDC Core and Financial-grade API (FAPI) signing requirements.
Exploitability
AV:NAC:HPR:NUI:NScope
S:UImpact
C:NI:HA:N5.9/CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:NOther