CVE-2026-9087
Keycloak: Insufficient verification proof scoping enables identity provider account linking attack and account compromise
6.4
MEDIUM
CVSS 3.1
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.
How to fix CVE-2026-9087
To remediate CVE-2026-9087, upgrade the affected package to a fixed version below.
- Maven/org.keycloak:keycloak-services—upgrade to 26.6.3 or later
Is CVE-2026-9087 being exploited?
No exploitation signal available. Neither CISA KEV nor a current EPSS score has been published for CVE-2026-9087.
Affected packages (1)
- from 0, < 26.6.3
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| osv | CVSS 3.1 | MEDIUM6.4 | CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:H/I:H/A:N |