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.
{
"severity": "MODERATE",
"github_reviewed": true,
"nvd_published_at": "2026-05-28T05:16:40Z",
"github_reviewed_at": "2026-07-01T21:23:28Z",
"cwe_ids": [
"CWE-347"
]
}