Keycloak: org.keycloak.protocol.oidc.grants.ciba: keycloak: information disclosure via cors header injection due to unvalidated jwt azp claim (Red Hat Red Hat build of Keycloak 26.4)
At a glance
- Source
- NVD
- EPSS
- EPSS 0.25 % · percentile 17 ()
- State
- PUBLISHED
- Published
- Updated
- Assigner
- redhat
- NVD status
- Modified
Description
A flaw was found in Keycloak. A remote attacker can exploit a Cross-Origin Resource Sharing (CORS) header injection vulnerability in Keycloak's User-Managed Access (UMA) token endpoint. This flaw occurs because the `azp` claim from a client-supplied JSON Web Token (JWT) is used to set the `Access-Control-Allow-Origin` header before the JWT signature is validated. When a specially crafted JWT with an attacker-controlled `azp` value is processed, this value is reflected as the CORS origin, even if the grant is later rejected. This can lead to the exposure of low-sensitivity information from authorization server error responses, weakening origin isolation, but only when a target client is misconfigured with `webOrigins: ["*"]`.
Weaknesses (CWE)
- CWE-346 — Origin Validation Error
References
Scores
| Version | Score | Vector | Scored by |
|---|---|---|---|
| CVSS 3.1 | LOW 3.7 | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N | redhat |
| CVSS 3.1 | LOW 3.7 | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N | NVD · secalert@redhat.com (Secondary) |
| CVSS 3.1 | MEDIUM 5.3 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N | NVD · nvd@nist.gov (Primary) |
Advisories
- GHSA-5v8v-xvjv-57x7 — Keycloak vulnerable to information disclosure via CORS header injection due to unvalidated JWT azp claim
European references
- ENISA EUVD · EUVD-2026-19201
- GCVE · GCVE-0-2026-37977
Affected configurations (NVD CPE)
cpe:2.3:a:redhat:build_of_keycloak:-:*:*:*:-:*:*:*
Affected products
| Product | Versions |
|---|---|
| Red Hat · Red Hat build of Keycloak 26.4 | unaffected 26.4.13-1 < * |
| Red Hat · Red Hat build of Keycloak 26.4 | unaffected 26.4-19 < * |
| Red Hat · Red Hat build of Keycloak 26.4 | unaffected 26.4-19 < * |
| Red Hat · Red Hat build of Keycloak 26.4.13 | |
| Red Hat · Red Hat build of Keycloak 26.6 | unaffected 26.6.3-3 < * |
| Red Hat · Red Hat build of Keycloak 26.6 | unaffected 26.6-6 < * |
| Red Hat · Red Hat build of Keycloak 26.6 | unaffected 26.6-6 < * |
| Red Hat · Red Hat build of Keycloak 26.6.3 |
Sources
| Source | Licence |
|---|---|
| CVE List (CVEProject cvelistV5) | CVE Program Terms of Use |
| EPSS (FIRST.org) | FIRST — attribution requested |
| ENISA EUVD | ENISA — reproduction authorised, source acknowledged |
| NVD (NIST) via fkie-cad/nvd-json-data-feeds | Public domain — this product uses data from the NVD API but is not endorsed or certified by the NVD |