High severity · published May 20, 2026
CVE-2026-9087
Keycloak: cross-session email verification proof not bound to upstream identity in first-broker-login
8.1
CVSS
0.3%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
Required
Confidentiality
High
Integrity
High
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.3% · higher than 24% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
RH
Red Hat build of Keycloak 26.4 · Red Hat
All versions, or not specified · source: vendor
RH
Red Hat build of Keycloak 26.6 · Red Hat
All versions, or not specified · source: vendor
BO
Build OF Keycloak · Redhat
All versions, or not specified · source: NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-9087
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-9087
access.redhat.com
https://access.redhat.com/errata/RHSA-2026:25097
access.redhat.com
https://access.redhat.com/errata/RHSA-2026:25098
access.redhat.com
https://access.redhat.com/errata/RHSA-2026:30049
access.redhat.com
https://access.redhat.com/errata/RHSA-2026:30050
Vendor Advisory
https://access.redhat.com/security/cve/CVE-2026-9087
Issue Tracking
https://bugzilla.redhat.com/show_bug.cgi?id=2480172
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