CVE-2026-18206: Keycloak-services: keycloak-services: client policy source-host wildcard domain matching bypass
- Is it exploited?
Not on CISA's list. CISA has not added it to the Known Exploited Vulnerabilities catalog as of . If CISA adds it, this page shows it as known exploited.
- How likely is exploitation in the next 30 days?
- 0.3%
EPSS score, percentile 24.5 of all scored records. A probability estimated by FIRST, not a report of exploitation.
- How severe?
- 3.7 Low
CVSS v3.1 base score, given by the CNA
- What should I do?
CISA has set no required action, because the vulnerability is not in KEV.
The CVE record links no vendor advisory, patch or mitigation.
- Which versions are affected?
Source: CISA KEV 2026.10.29, as of ; FIRST EPSS, as of ; CVE List, as of . About the data.
What to do
Workaround (from the CVE record)
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.
Advisories and patches
The CVE record links no vendor advisory, patch or mitigation.
This summary is based on the CVE record as of . Check the vendor's advisory before you act: affected versions and fixes can change.
Affected products and versions
As listed in the CVE record.
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Versions not listed are: affected.
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Versions not listed are: affected.
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Versions not listed are: affected.
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Versions not listed are: unaffected.
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Versions not listed are: unaffected.
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Versions not listed are: unaffected.
Source: CVE List, as of . About the data.
About this vulnerability
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…
Summary: CVE record, as of .
- CISA has not added CVE-2026-18206 to its Known Exploited Vulnerabilities (KEV) catalog, as of 29 Oct 2026.
- The CVE record was published on 31 Jul 2026.
- The CVE record carries a CVSS v3.1 base score of 3.7 (Low), given by its CNA.
- FIRST's EPSS model puts the probability of exploitation in the next 30 days at 0.3% (percentile 24.5), as of 29 Oct 2026. EPSS is a statistical estimate, not a report of exploitation.
- CISA's SSVC assessment in the CVE record: exploitation none, automatable no, technical impact partial.
- The credits in the CVE record name OpenAI as finder.
Source: CISA KEV 2026.10.29, as of ; CVE List, as of ; FIRST EPSS, as of . About the data.
Description
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.
Source: CVE List, as of . About the data.
Weakness
CWE-20
CWE and CAPEC are maintained by MITRE; the entries are those named in the CVE record.
Timeline
| Date | Event |
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| CVE record published | |
| CVE record last updated |
References
2
Known exploited Red Hat vulnerabilities
- CVE-2015-3246: Red Hat Libuser Race Condition Vulnerability
- CVE-2015-5287: Red Hat Automatic Bug Reporting Tool Privilege Escalation Vulnerability
- CVE-2018-14667: Red Hat JBoss RichFaces Framework Expression Language Injection Vulnerability
- CVE-2021-3560: Red Hat Polkit Incorrect Authorization Vulnerability
- CVE-2021-4034: Red Hat Polkit Out-of-Bounds Read and Write Vulnerability