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3.7 Low

CVE-2026-37977 A flaw was found in Keycloak

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: ["*"]`.

Affected products and versions

Product Affected versions Fixed in
Red Hat Build of Keycloak Versions not published
Red Hat build of Keycloak 26.6.3 Versions not published
Red Hat build of Keycloak 26.6 26.6 earliest → < 26.6-6 26.6-6
Red Hat build of Keycloak 26.6.4 Versions not published
Red Hat build of Keycloak 26.4 26.4 earliest → < 26.4-19 26.4-19
Red Hat build of Keycloak 26.4.13 Versions not published

References

Timeline

  1. Published
  2. Last modified

Other CVEs of Red Hat Build of Keycloak

The 266 CVEs of Red Hat Build of Keycloak →
CVE-2026-97847 Keycloak-services: keycloak-services: client manager can substitute sessionless token principal via hardcoded-claim mappers to obtain realm administrator authority 7.1 High CVE-2026-97175 Keycloak-services: keycloak-services: unverified idp email auto-linking enables account takeover 8.8 High CVE-2026-97174 Keycloak-services: keycloak-services: ciba sub parameter injection causes attacker authentication to issue victim tokens 6.8 Medium CVE-2026-96453 Org.keycloak/keycloak-admin-cli: keycloak-admin-cli: kcadm custom truststore accepts arbitrary self-signed certificates 8.0 High
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