---
id: CVE-2026-18217
title: >-
  A flaw was found in the SAML protocol implementation of Keycloak, an
  open-source identity and access management solution
summary: >-
  A flaw was found in the SAML protocol implementation of Keycloak, an
  open-source identity and access management solution. The issue occurs when
  Keycloak handles SAML authentication requests using the HTTP-Redirect binding.
  If a client is…
severity: low
cvss: 3.4
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:N/I:L/A:N'
cwe:
  - CWE-20
vendor: redhat
product: build_of_keycloak
affected:
  - build_of_keycloak
published: '2026-07-31'
updated: '2026-08-07'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-18217'
references:
  - url: 'https://access.redhat.com/security/cve/CVE-2026-18217'
    label: secalert@redhat.com
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2508311'
    label: secalert@redhat.com
tags:
  - nvd
epss: 0.00193
epssPercentile: 0.09195
ingestedAt: '2026-08-08T14:22:57.544Z'
---

## Overview

A flaw was found in the SAML protocol implementation of Keycloak, an open-source identity and access management solution. The issue occurs when Keycloak handles SAML authentication requests using the HTTP-Redirect binding. If a client is configured with a wildcard redirect URL, an attacker can craft a request that includes malicious parameters. When a user authenticates, Keycloak appends its legitimate response to the attacker's parameters. This can cause some service providers to process the attacker's data instead of the real login information, potentially leading to a user being logged into the wrong account.

## Affected

- `build_of_keycloak`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.