CVE-2026-9087CWE-639

Keycloak: cross-session email verification proof not bound to upstream identity in first-broker-login

Medium · published May 20, 2026

CVSS v3.1
6.4
EPSS
0%
Percentile
32.1
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v3.1
6.4 · MEDIUM
Vector
CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:H/I:H/A:N
CVSS v4.0
Not supplied
EPSS
0.00392 · 32.1th percentile
Weakness
CWE-639 · Authorization Bypass Through User-Controlled Key
Published
2026-05-20T16:13Z
EPSS history
Timeline
  • 20 MAY 16:13Z
    Keycloak: cross-session email verification proof not bound to upstream identity in first-broker-login
    cvelistv5