---
id: CVE-2026-9087
title: A flaw was found in Keycloak
summary: >-
  A flaw was found in Keycloak. The cross-session verification proof is keyed
  only by (local userId,

  idpAlias) and is not bound to the upstream identity that was actually
  verified, so a second upstream account on the same IdP can consume i…
severity: medium
cvss: 6.4
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:H/I:H/A:N'
cwe:
  - CWE-639
published: '2026-05-20'
updated: '2026-06-26'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-9087'
references:
  - url: 'https://access.redhat.com/errata/RHSA-2026:25097'
    label: secalert@redhat.com
  - url: 'https://access.redhat.com/errata/RHSA-2026:25098'
    label: secalert@redhat.com
  - url: 'https://access.redhat.com/errata/RHSA-2026:30049'
    label: secalert@redhat.com
  - url: 'https://access.redhat.com/errata/RHSA-2026:30050'
    label: secalert@redhat.com
  - url: 'https://access.redhat.com/security/cve/CVE-2026-9087'
    label: secalert@redhat.com
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2480172'
    label: secalert@redhat.com
tags:
  - nvd
epss: 0.00392
epssPercentile: 0.30464
ingestedAt: '2026-06-26T16:43:14.181Z'
---

## Overview

A flaw was found in Keycloak. The cross-session verification proof is keyed only by (local userId,
idpAlias) and is not bound to the upstream identity that was actually verified, so a second upstream account on the same IdP can consume it and get linked to the victim's local account.

## Remediation

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