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 :
May 20, 2026, 5:32 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
Affected Products
The following products are affected by CVE-2026-9087
vulnerability.
Even if cvefeed.io is aware of the exact versions of the
products
that
are
affected, the information is not represented in the table below.
No affected product recoded yet
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 3.1 | MEDIUM | [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/security/cve/CVE-2026-9087 | |
| https://bugzilla.redhat.com/show_bug.cgi?id=2480172 |
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.
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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