CVE-2026-97174
A flaw was found in the Client-Initiated Backchannel Authentication (CIBA) implementation of Keycloak.
Impact
A flaw was found in the Client-Initiated Backchannel Authentication (CIBA) implementation of Keycloak. The CIBA endpoint fails to properly validate the sub parameter, allowing it to be stored as an additional request parameter. During the token issuance process, this injected value overwrites the legitimate subject identifier. This allows an attacker to authenticate as themselves but receive security tokens belonging to a different victim user, leading to unauthorized account access.
An attacker can exploit this over the network, with a regular user account, without any action by a user. Specific conditions have to be met, which makes an attack harder. If it succeeds: high risk of data being read, high risk of data or systems being changed.
Affected products · Red Hat
| Product | Affected versions |
|---|---|
| Red Hat build of Keycloak 26.6 | Versions patch: 26.6.8-2, patch: 26.6-24 |