Keycloak 26.4.0 <= 26.8.0 Token Introspection Audience Bypass (CVE-2026-105306)

medium Nessus Plugin ID 363811

Synopsis

An identity and access management application running on the remote host is affected by a vulnerability.

Description

The version of Keycloak installed on the remote host is 26.4.0 through 26.8.0. It is, therefore, affected by a token introspection audience bypass vulnerability. An attacker able to use dynamic client registration can register a client that passes token introspection for tokens that were not issued for it, bypassing the intended audience restriction.

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

Solution

Refer to the vendor advisory for patch or mitigation information.

Plugin Details

Severity: Medium

ID: 363811

File Name: keycloak_CVE-2026-105306.nasl

Version: 1.1

Type: Local

Agent: unix

Family: Misc.

Published: 10/7/2026

Updated: 10/7/2026

Configuration: Enable thorough checks (optional)

Supported Sensors: Nessus Agent, Nessus

Risk Information

VPR

Risk Factor: Low

Score: 3

Percentile: 23.68

CVSS v2

Risk Factor: Medium

Base Score: 6.8

Vector: CVSS2#AV:N/AC:L/Au:S/C:C/I:N/A:N

CVSS Score Source: CVE-2026-105306

CVSS v3

Risk Factor: Medium

Base Score: 6.5

Vector: CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N

Vulnerability Information

CPE: cpe:/a:keycloak:keycloak

Required KB Items: Host/local_checks_enabled, Host/uname, installed_sw/Keycloak

Vulnerability Publication Date: 10/2/2026

Reference Information

CVE: CVE-2026-105306

Detections

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