Medium 6.5Published Jul 31, 2026

CVE-2026-18203Keycloak-services: keycloak-services: group policy extendchildren matches sibling group path prefixes

Updated under an hour ago (Oct 28, 2026, 3:23 AM ET)

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It affects Red Hat Build of Keycloak and 4 other products. Add what you run to find out whether that includes you.

No exploitation reported and no EPSS estimate yet.

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Every CVE for Red Hat Build of Keycloak

Exploited in the last 30 days

A flaw was found in the group policy evaluation logic of Keycloak, an identity and access management solution. When a group policy is set to extend permissions to child groups, the system incorrectly uses a simple text-based prefix check to verify group membership. This allows a user who belongs to a different group with a similar starting name to bypass security checks and gain unauthorized access to administrative functions or protected resources.

CVSS: 6.5 MEDIUM (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N
Weakness (CWE): CWE-863
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: redhat
NVD analysis: Analyzed
Record last updated: Aug 31, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

Red Hat Red Hat Build of Keycloak redhat:build_keycloak	All versions	CNA record
Red Hat Red Hat Data Grid 8 redhat:jboss_data_grid	8	CNA record
Red Hat Red Hat JBoss Enterprise Application Platform Expansion Pack redhat:jbosseapxp	Versions not stated	CNA record
Red Hat Red Hat Single Sign-On 7 redhat:red_hat_single_sign_on	7	CNA record
redhat build_of_keycloak redhat:build_of_keycloak	all versions	NVD

References

References

https://access.redhat.com/security/cve/CVE-2026-18203	vdb-entry, x-refsource-redhat, vendor-advisory
https://bugzilla.redhat.com/show_bug.cgi?id=2508291	issue-tracking, x-refsource-redhat, vendor-advisory

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.