Review reviewHigh

CVE-2026-9087

Red Hat Red Hat build of Keycloak 26.4, Red Hat build of Keycloak 26.4.13, Red Hat build of Keycloak 26.6

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.

CVSS: 8.1
EPSS: 0.31%
CISA KEV: Not listed
Published: 2026.05.21

PRIORITY ASSESSMENT

Review review

The CVSS severity warrants an early asset and exposure review.

Known exploitationNot established by KEV

Exploit probability0.31%

Technical severityCVSS 8.1

Vulnerability overview

Affected product and versions

Product: Red Hat Red Hat build of Keycloak 26.4, Red Hat build of Keycloak 26.4.13, Red Hat build of Keycloak 26.6
Affected versions: See the vendor advisory and NVD configuration data
Fixed versions: No verified fixed-version field is available yet

Recommended response sequence

Confirm exposure before applying a vendor-supported change.

Full remediation guide

1
Identify
Confirm that Red Hat Red Hat build of Keycloak 26.4, Red Hat build of Keycloak 26.4.13, Red Hat build of Keycloak 26.6 and an affected version are present.
2
Prioritize
Combine exploitation signals with asset exposure and business criticality.
3
Remediate
Follow the vendor advisory or supported update path and preserve rollback options.
4
Verify
Recheck the version, service health, access paths, and relevant logs.

Technical data

CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N
CWE: CWE-639