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CVE-2026-18203

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

Published: Jul 31, 2026Updated: Aug 7, 2026 Sources: CVE List NVDCWE-863
6.5MEDIUM
NVD MITRE
EPSS Score
0.2%
Top 92.1%
CISA KEV
Not in KEV
Exploits
No Known Exploits
Remediation
Patch Available
Self-Check
OpenVAS

Description

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.

No summary for this CVE yet.

CVSS Vector Breakdown

AV:NAC:LPR:LUI:NS:UC:NI:HA:N
Exploitability
AV:NAttack Vector
Network
AC:LAttack Complexity
Low
PR:LPrivileges Required
Low
UI:NUser Interaction
None
Scope
S:UScope
Unchanged
Impact
C:NConfidentiality
None
I:HIntegrity
High
A:NAvailability
None
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Weaknesses

CWE-863

Affected Products

Red Hat
commercial·USaka redhat
Red Hat Build of Keycloak
Web & CMS Plugins
Red Hat Data Grid 8On-premDatabase
Databases / cache-message-queue
Red Hat JBoss Enterprise Application Platform Expansion PackOn-premOS
Operating Systems / linux-distro
Red Hat Single Sign-On 7On-premSecurity Product
Security Products / identity-access-mgmt
build of keycloakOn-prem
Operating Systems / linux-distro

Exploitability

Official Patch Available
Workaround Available
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Attack Graph

Products CVE Techniques Tactics

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MITRE ATT&CK

2 techniques
Initial Access
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References

https://access.redhat.com/security/cve/CVE-2026-18203
access.redhat.com
https://bugzilla.redhat.com/show_bug.cgi?id=2508291
bugzilla.redhat.com

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