high8.1
CVE-2026-4636
Keycloak: UMA Policy Resource Injection Allows Unauthorized Cross-User Permission Grants
Impact
A flaw was found in Keycloak. An authenticated user with the uma_protection role can bypass User-Managed Access (UMA) policy validation. This allows the attacker to include resource identifiers owned by other users in a policy creation request, even if the URL path specifies an attacker-owned resource. Consequently, the attacker gains unauthorized permissions to victim-owned resources, enabling them to obtain a Requesting Party Token (RPT) and access sensitive information or perform unauthorized actions.
Affected packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| maven | org.keycloak:keycloak-services | < 26.5.7 | 26.5.7 |
Affected products
| Vendor | Product | Affected versions |
|---|---|---|
| Redhat | Build Of Keycloak | All versions Versions 26.2, 26.2.15, 26.4, 26.4.11 |
Weakness classification
References
- NVD record
- CVE.org record
- GitHub advisory
- https://access.redhat.com/errata/RHSA-2026:6475
- https://access.redhat.com/errata/RHSA-2026:6476
- https://access.redhat.com/errata/RHSA-2026:6477
- https://access.redhat.com/errata/RHSA-2026:6478
- https://access.redhat.com/security/cve/CVE-2026-4636
- https://bugzilla.redhat.com/show_bug.cgi?id=2450251
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-4636.json
- https://github.com/advisories/GHSA-f2hx-5fx3-hmcv
- https://nvd.nist.gov/vuln/detail/CVE-2026-4636
- https://github.com/keycloak/keycloak/issues/47717
- https://github.com/keycloak/keycloak/commit/995832f8b74b02833d106c8788bb7a78634aa725