CVE-2026-9087
Keycloak: cross-session email verification proof not bound to upstream identity in first-broker-login
Description
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.
INFO
Published Date :
May 20, 2026, 5:16 p.m.
Last Modified :
June 10, 2026, 10:17 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 3.1 | MEDIUM | [email protected] | ||||
| CVSS 3.1 | HIGH | [email protected] |
Solution
- Update Keycloak to the latest version.
- Apply vendor patches for Keycloak.
- Ensure cross-session verification is properly bound.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-9087.
| URL | Resource |
|---|---|
| https://access.redhat.com/errata/RHSA-2026:25097 | |
| https://access.redhat.com/errata/RHSA-2026:25098 | |
| https://access.redhat.com/security/cve/CVE-2026-9087 | Vendor Advisory |
| https://bugzilla.redhat.com/show_bug.cgi?id=2480172 | Issue Tracking Vendor Advisory |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-9087 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-9087
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-9087 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-9087 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
CVE Modified by [email protected]
Jun. 10, 2026
Action Type Old Value New Value Added Reference https://access.redhat.com/errata/RHSA-2026:25097 -
CVE Modified by [email protected]
Jun. 10, 2026
Action Type Old Value New Value Added Reference https://access.redhat.com/errata/RHSA-2026:25098 -
Initial Analysis by [email protected]
Jun. 02, 2026
Action Type Old Value New Value Added CVSS V3.1 AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N Added CPE Configuration OR *cpe:2.3:a:redhat:build_of_keycloak:-:*:*:*:-:*:*:* Added Reference Type Red Hat, Inc.: https://access.redhat.com/security/cve/CVE-2026-9087 Types: Vendor Advisory Added Reference Type Red Hat, Inc.: https://bugzilla.redhat.com/show_bug.cgi?id=2480172 Types: Issue Tracking, Vendor Advisory -
New CVE Received by [email protected]
May. 20, 2026
Action Type Old Value New Value Added Description 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. Added CVSS V3.1 AV:N/AC:H/PR:L/UI:R/S:U/C:H/I:H/A:N Added CWE CWE-639 Added Reference https://access.redhat.com/security/cve/CVE-2026-9087 Added Reference https://bugzilla.redhat.com/show_bug.cgi?id=2480172