CVE-2026-18203
CVE-2026-18203: 1 tracked advisory record across Red Hat. Compare source-reported impact, fixes and remediation.
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Red Hat
1 advisory- Advisory severityMedium6.5
Medium [CVE-2026-18203] Group policy extendChildren matches sibling group path prefixes
CVE-2026-18203Source published Source updated
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. The Red Hat Product Security team has assessed the severity of this vulnerability as Moderate, given that exploitation requires a specific group naming collision and the extendChildren policy setting to be active. Successful exploitation allows an attacker to gain unauthorized integrity-impacting permissions within the realm. The…
- Affected products in this advisory
- Red Hat Build of Keycloak
- Source-reported affected versions
- Affected-version details not available in this record.
- Source-reported fixed versions
- No fixed-version detail extracted. This does not mean no fix exists.
- Mitigation guidance
- 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.
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