A flaw was found in Keycloak. The SingleUseObjectProvider, a global key-value store, lacks proper type and namespace isolation. This vulnerability allows an unauthenticated attacker to forge authorization codes. Successful exploitation can lead to the creation of admin-capable access tokens, resulting in privilege escalation.

Keycloak installed on the remote host is 26.2.x prior to 26.2.15, 26.4.x prior to  26.4.11, 26.5.x prior to 26.5.7 are affected by multiple vulnerabilities:

  - A privilege escalation flaw exists due to improper isolation in the SingleUseObjectProvider. An     unauthenticated, remote attacker can forge authorization codes and potentially obtain admin-capable     access tokens. (CVE-2026-4282)

  - A denial of service flaw exists in the OpenID Connect token endpoint. An unauthenticated, remote     attacker can exhaust server CPU and memory by sending an excessively long scope parameter.
    (CVE-2026-4634)

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

There are packages installed that are affected by a vulnerability referenced in the following CVE:

  - A flaw was found in Keycloak. The SingleUseObjectProvider, a global key-value store, lacks proper type and
    namespace isolation. This vulnerability allows an unauthenticated attacker to forge authorization codes.
    Successful exploitation can lead to the creation of admin-capable access tokens, resulting in privilege
    escalation. (CVE-2026-4282)

ID	Name	Product	Family	Type	Severity
330085	Keycloak 26.2 < 26.2.15 / 26.4 < 26.4.11 / 26.5 < 26.5.7 Multiple Vulnerabilities	Nessus	Misc.	Local	high
439850	SCA: security update for org.keycloak:keycloak-services (GHSA-hj93-h7pg-fh6v)	Tenable Cloud Security	SCA Checks	Local	high
439850	SCA: security update for org.keycloak:keycloak-services (GHSA-hj93-h7pg-fh6v)	Tenable Self-Hosted Container Security	SCA Checks	Local	high

Detections

Analytics

CVE-2026-4282

high

Tenable Plugins

high

high

high