Copyright © 2012 Red Hat, Inc. All rights reserved. Moderate 2026-07-28T12:19:00 keycloak-services: keycloak-services: Google external access-token exchange bypasses hosted-domain restriction 6.8 CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N CWE-862

Keycloak allows users to log in using Google accounts and can be configured to only allow users from specific Google Workspace domains. A flaw was found where the token exchange feature, which allows swapping a Google token for a Keycloak token, does not check these domain restrictions. This means an attacker with a valid Google account from a different domain could bypass the security check and gain access to the Keycloak realm.

Keycloak allows users to log in using Google accounts and can be configured to only allow users from specific Google Workspace domains. A flaw was found where the token exchange feature, which allows swapping a Google token for a Keycloak token, does not check these domain restrictions. This means an attacker with a valid Google account from a different domain could bypass the security check and gain access to the Keycloak realm.

The Red Hat Product Security team has assessed the severity of this vulnerability as Moderate, given that it requires the preview Token Exchange V1 feature to be enabled and specific client permissions to be granted. Successful exploitation allows an attacker to bypass Google hosted-domain restrictions and obtain unauthorized Keycloak tokens. The vulnerability's root cause is a missing validation check for the hosted-domain claim during the external access-token exchange process. Red Hat would like to thank Paul Bottinelli (Trail of Bits) for reporting this issue. Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability. Red Hat Build of Keycloak Affected keycloak-services Red Hat Build of Keycloak Affected rhbk-keycloak-rhel9/rhbk-keycloak-rhel9 Red Hat Build of Keycloak Affected rhbk-openshift-rhel9/rhbk-openshift-rhel9 Red Hat Data Grid 8 Not affected keycloak-services Red Hat JBoss Enterprise Application Platform Expansion Pack Not affected keycloak-services Red Hat Single Sign-On 7 Not affected keycloak-services https://www.cve.org/CVERecord?id=CVE-2026-18214 https://nvd.nist.gov/vuln/detail/CVE-2026-18214