CVE-2026-18206
Keycloak-services: keycloak-services: client policy source-host wildcard domain matching bypass
A flaw was found in the keycloak-services component of Keycloak, which provides identity and access management services. The issue occurs when a realm administrator uses a wildcard domain (like *.example.com) to restrict which hosts can register or update clients. Due to improper validation, the system accepts any hostname that ends with the specified domain suffix, even if it is not a legitimate subdomain. An attacker who can control the reverse DNS of their connection can bypass these host-based restrictions, potentially allowing unauthorized client modifications.
Fixes and workarounds
Workaround
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.
Source: CNA: redhatAffected products and versions
| Product | Versions | Authority |
|---|---|---|
| Red Hat build of Keycloak 26.6 Red Hat rhbk/keycloak-operator-bundle
https://catalog.redhat.com/software/containers/ |
≥ 26.6.8-2; < * (unaffected, rpm)
Other versions: affected |
CNA: redhat |
| Red Hat build of Keycloak 26.6 Red Hat rhbk/keycloak-rhel9
https://catalog.redhat.com/software/containers/ |
≥ 26.6-24; < * (unaffected, rpm)
Other versions: affected |
CNA: redhat |
| Red Hat build of Keycloak 26.6 Red Hat rhbk/keycloak-rhel9-operator
https://catalog.redhat.com/software/containers/ |
≥ 26.6-24; < * (unaffected, rpm)
Other versions: affected |
CNA: redhat |
| Red Hat build of Keycloak 26.6.8 Red Hat keycloak-services
https://access.redhat.com/downloads/content/package-browser/ |
Range not reported
Other versions: unaffected |
CNA: redhat |
| Red Hat build of Keycloak 26.6.8 Red Hat rhbk-keycloak-rhel9/rhbk-keycloak-rhel9
https://access.redhat.com/downloads/content/package-browser/ |
Range not reported
Other versions: unaffected |
CNA: redhat |
| Red Hat build of Keycloak 26.6.8 Red Hat rhbk-openshift-rhel9/rhbk-openshift-rhel9
https://access.redhat.com/downloads/content/package-browser/ |
Range not reported
Other versions: unaffected |
CNA: redhat |
| Red Hat Data Grid 8 Red Hat keycloak-services
https://access.redhat.com/downloads/content/package-browser/ |
Range not reported
Other versions: unaffected |
CNA: redhat |
| Red Hat JBoss Enterprise Application Platform Expansion Pack Red Hat keycloak-services
https://access.redhat.com/jbossnetwork/restricted/listSoftware.html |
Range not reported
Other versions: unaffected |
CNA: redhat |
| Red Hat Single Sign-On 7 Red Hat keycloak-services
https://access.redhat.com/downloads/content/package-browser/ |
Range not reported
Other versions: unaffected |
CNA: redhat |
Version ranges are source assertions. Check the vendor advisory and your installed configuration before determining exposure.
CVSS assessments
| Version / score | Vector | Authority |
|---|---|---|
| 3.1 / 3.7 low |
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N | CNA: redhat |
Exploit evidence
No exploit evidence in collected sources. This is not proof of no exploitation.
References
- https://access.redhat.com/errata/RHSA-2026:95761CNA: redhat · vendor-advisory, x_refsource_REDHAT
- https://access.redhat.com/errata/RHSA-2026:95762CNA: redhat · vendor-advisory, x_refsource_REDHAT
- https://access.redhat.com/security/cve/CVE-2026-18206CNA: redhat · vdb-entry, x_refsource_REDHAT
- https://bugzilla.redhat.com/show_bug.cgi?id=2508292CNA: redhat · issue-tracking, x_refsource_REDHAT
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