3.7

CVE-2026-18206: Keycloak-services: keycloak-services: client policy source-host wildcard domain matching bypass

Analyzed
Published 31-07-2026Last modified 31-08-2026

Vulnerability summary

CVE-2026-18206 is a low (CVSS 3.7) Improper Input Validation vulnerability in redhat build_of_keycloak. EPSS estimates a 0.32% chance of exploitation in the next 30 days, higher than 23.2% of scored vulnerabilities.

Overall risk
15/100
0100
Low · default modelHow is this calculated?
CVSS score
3.7/10
010
Low · v3.1 (CVE.org)
EPSS score
0.32%
0%100%
Low · +0.11 pp in 30 days
KEVNot listedNot listed by any tracked catalog.
RansomwareNot flaggedNo ransomware use recorded.
Public exploits0No public exploits recorded

Timeline

  1. 31-07-2026
    PublishedVulnerability first disclosed.
  2. 31-08-2026
    Last modifiedVulnerability information updated.

Description

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.

CVSS metrics

2 scores · 2 sources · 1 version

EPSS trend

Probability

0.32%

Chance of exploitation in the next 30 days

Percentile

23%

Versus all other CVEs

30-day change

Increase +0.11 pp

From 0.20% on 22-09-2026

22-09-202622-10-2026

Known exploited

Compare KEV catalogs
CISA KEV

Not in the CISA KEV catalog.

ENISA CNW

Not in the ENISA CNW catalog.

CIRCL

Not in the CIRCL catalog.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Redhat1 product

1 vendor · 1 product

References

2 links