Detections
Analytics

Keycloak < 26.5.4 Multiple Vulnerabilities

medium Nessus Plugin ID 300554

Synopsis

The remote host is affected by multiple vulnerabilities.

Description

Keycloak versions installed prior to 26.5.4 are affected by multiple vulnerabilities, including:

 - The Keycloak Authorization header parser is overly permissive regarding the formatting of the 'Bearer' authentication scheme. It accepts non-standard characters (such as tabs) as separators and tolerates case variations that deviate from RFC 6750 specifications. (CVE-2026-0707)

 - A flaw was identified in the Docker v2 authentication endpoint of Keycloak, where tokens continue to be issued even after a Docker registry client has been administratively disabled.
 This means that turning the client 'Enabled' setting to OFF does not fully prevent access.
 (CVE-2026-2733)

 - A flaw was found in Keycloak's SAML brokering functionality. When Keycloak is configured as a client in a SAML setup, it fails to validate the NotOnOrAfter timestamp within the SubjectConfirmationData. This allows an attacker to delay the expiration of SAML responses.
 (CVE-2026-1190)

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

Solution

Upgrade Keycloak to 26.5.4 or later.

See Also

https://www.keycloak.org/2026/02/keycloak-2654-released

Plugin Details

Severity: Medium

ID: 300554

File Name: keycloak_26_5_4.nasl

Version: 1.1

Type: local

Agent: unix

Family: Misc.

Published: 3/4/2026

Updated: 3/4/2026

Configuration: Enable thorough checks (optional)

Supported Sensors: Nessus Agent, Nessus

Risk Information

VPR

Risk Factor: Medium

Score: 4.0

CVSS v2

Risk Factor: Medium

Base Score: 5

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

CVSS Score Source: CVE-2026-0707

CVSS v3

Risk Factor: Medium

Base Score: 5.3

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

Vulnerability Information

CPE: cpe:/a:keycloak:keycloak

Required KB Items: Host/local_checks_enabled, Host/uname

Patch Publication Date: 2/20/2026

Vulnerability Publication Date: 2/20/2026

Reference Information

CVE: CVE-2025-5416, CVE-2026-0707, CVE-2026-1190, CVE-2026-2575, CVE-2026-2733