Bug 2539387 (CVE-2026-96547)

Summary: CVE-2026-96547 keycloak-services: keycloak-services: DCR registration-time claim-path gap allows forging realm_access.roles
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: aschwart, aszczucz, boliveir, drichtar, mposolda, pjindal, rmartinc, security-response-team, ssilvert, sthorger, vmuzikar
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in the Dynamic Client Registration component of Keycloak, an open-source identity and access management solution. The issue occurs because the system does not properly restrict which claim names can be used when setting up new clients. An attacker with valid registration credentials could create a client that incorrectly maps standard user profile information to sensitive security roles, potentially allowing them to gain unauthorized privileges on external applications that trust Keycloak tokens.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:
Deadline: 2026-12-22   

Description OSIDB Bzimport 2026-09-23 12:38:47 UTC 
A flaw was found in Keycloak Dynamic Client Registration (DCR) within the org.keycloak.services.clientregistration.policy package. The client registration policy validates allowed mapper types but fails to restrict the claim.name value during the registration process. An attacker possessing a valid Initial Access Token (IAT) can register a new client configured with an oidc-usermodel-attribute-mapper that maps a user-editable profile field, such as firstName, directly to the realm_access.roles claim. When a user subsequently authenticates through this client, the mapper injects the attacker-controlled field value into the realm_access.roles claim of the issued token. This allows an attacker to forge or corrupt the realm roles claim in tokens provided to external relying parties. While Keycloak internal authorization and the Admin REST API are unaffected because they evaluate the user role model directly, external applications relying on the realm_access.roles claim for access control are vulnerable to privilege escalation.