---
id: CVE-2026-18206
title: >-
  A flaw was found in the keycloak-services component of Keycloak, which
  provides identity and access management services
summary: >-
  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 …
severity: low
cvss: 3.7
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N'
cwe:
  - CWE-20
vendor: redhat
product: build_of_keycloak
affected:
  - build_of_keycloak
published: '2026-07-31'
updated: '2026-08-07'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-18206'
references:
  - url: 'https://access.redhat.com/security/cve/CVE-2026-18206'
    label: secalert@redhat.com
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2508292'
    label: secalert@redhat.com
tags:
  - nvd
epss: 0.00316
epssPercentile: 0.21919
ingestedAt: '2026-08-08T14:22:57.344Z'
---

## Overview

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.

## Affected

- `build_of_keycloak`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.