Medium [CVE-2026-18214] Google external access-token exchange bypasses hosted-domain restriction
This medium-severity Red Hat Linux advisory covers CVE-2026-18214 affecting Red Hat Build of Keycloak.
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Summary
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. Weakness: CWE-862.
Affected Red Hat products: Red Hat Build of Keycloak. Red Hat lists Red Hat Data Grid 8; Red Hat JBoss Enterprise Application Platform Expansion Pack; Red Hat Single Sign-On 7 as not affected.
Red Hat does not currently list a fixing RHSA for this CVE.
Affected versions
No affected-version range was extracted from the source record. The vendor advisory is authoritative — check it before change work.
Official advisory · high-confidence parse· fetched 9 days ago·verify at source
Fixed versions
No fixed release is recorded yet. That does not prove no patch exists — confirm against the vendor advisory.
Official advisory · high-confidence parse· fetched 9 days ago·verify at source
Mitigation checklist
- 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.
Official advisory · high-confidence parse· fetched 9 days ago·verify at source
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