CVE-2026-97174 · Package
NO FIX YET
Keycloak's Client-Initiated Backchannel Authentication (CIBA) endpoint does not validate the sub parameter, so it can be stored as an extra request parameter. During token issuance that value overwrites the real subject, so an attacker who signs in as themselves can receive security tokens for another user.
first public Nov 5, 2026 · 1 source
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Only deployments where the CIBA feature is used can be exposed, because the flaw sits in the CIBA endpoint. Teams running Keycloak without CIBA clients have a smaller exposure, but the sources do not state whether CIBA is enabled by default. Teams that run Keycloak as a managed service should ask the provider for the patched version.
Not affected if ciba-disabled, managed-hosting
Who cares authentication, identity, keycloak, self-hosted
kc.sh --version or the server banner in logs; compare it against the fixed versions below.No fix yet, per the sources.
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.
This page as .md · .json · CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N
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