CVE-2026-97848 Keycloak-services: keycloak-services: protocol mapper with jsontype=json bypasses token sanitization

Description

A flaw was found in the token sanitization logic of Keycloak, an open source identity and access management solution. The issue occurs when a protocol mapper is configured to emit structured claims using the JSON type. The security check designed to remove unauthorized role mappings only looks for standard Java maps and fails to recognize Jackson based JSON objects. This allows an attacker to inject forged client roles into security tokens, which could lead to unauthorized access to protected resources.

Exploitable remotely over the network, with an ordinary account and without any user action; an attacker can seriously compromise confidentiality, integrity or availability.

Attack vector

Network

Attack complexity

Low

Privileges required

Low

Interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

High

Availability

None

Affected products and versions