---
id: CVE-2026-2603
title: A flaw was found in Keycloak
summary: >-
  A flaw was found in Keycloak. A remote attacker could bypass security controls
  by sending a valid SAML response from an external Identity Provider (IdP) to
  the Keycloak SAML endpoint for IdP-initiated broker logins. This allows the
  attac…
severity: high
cvss: 8.1
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N'
cwe:
  - CWE-306
  - CWE-306
vendor: redhat
product: build_of_keycloak
affected:
  - 'build_of_keycloak >= 26.2, < 26.2.14'
  - 'build_of_keycloak >= 26.4, < 26.4.10'
patched:
  - build_of_keycloak 26.4.10
published: '2026-03-18'
updated: '2026-08-18'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-2603'
references:
  - url: 'https://access.redhat.com/errata/RHSA-2026:3925'
    label: secalert@redhat.com
  - url: 'https://access.redhat.com/errata/RHSA-2026:3926'
    label: secalert@redhat.com
  - url: 'https://access.redhat.com/errata/RHSA-2026:3947'
    label: secalert@redhat.com
  - url: 'https://access.redhat.com/errata/RHSA-2026:3948'
    label: secalert@redhat.com
  - url: 'https://access.redhat.com/security/cve/CVE-2026-2603'
    label: secalert@redhat.com
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2440300'
    label: secalert@redhat.com
  - url: 'https://access.redhat.com/errata/RHSA-2026:3925'
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
  - url: 'https://access.redhat.com/errata/RHSA-2026:3926'
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
  - url: 'https://access.redhat.com/errata/RHSA-2026:3947'
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
  - url: 'https://access.redhat.com/errata/RHSA-2026:3948'
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
  - url: 'https://access.redhat.com/security/cve/CVE-2026-2603'
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2440300'
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2440300'
    label: 134c704f-9b21-4f2e-91b3-4a467353bcc0
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-2603.json
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
tags:
  - nvd
epss: 0.00425
epssPercentile: 0.36407
ingestedAt: '2026-08-18T18:21:28.224Z'
---

## Overview

A flaw was found in Keycloak. A remote attacker could bypass security controls by sending a valid SAML response from an external Identity Provider (IdP) to the Keycloak SAML endpoint for IdP-initiated broker logins. This allows the attacker to complete broker logins even when the SAML Identity Provider is disabled, leading to unauthorized authentication.

## Affected

- `build_of_keycloak >= 26.2, < 26.2.14`
- `build_of_keycloak >= 26.4, < 26.4.10`

## Remediation

Upgrade past the affected range:

- `build_of_keycloak 26.4.10`