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CVE-2026-9087

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

Published: May 20, 2026Updated: May 20, 2026 Sources: CVE List NVD
NVD MITRE
6.4CVSS
MEDIUM

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.

EPSS Score
N/A
CISA KEV
Not in KEV
Exploits
No Known Exploits
Remediation
Workaround Only

CVSS Vector Breakdown

AV:NAC:HPR:LUI:RS:UC:HI:HA:N
Exploitability
AV:NAttack Vector
Network
AC:HAttack Complexity
High
PR:LPrivileges Required
Low
UI:RUser Interaction
Required
Scope
S:UScope
Unchanged
Impact
C:HConfidentiality
High
I:HIntegrity
High
A:NAvailability
None

Weaknesses

CWE-639

Affected Products

Red Hat Build of Keycloak
Red Hat

Attack Graph

Products CVE Techniques Tactics

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Exploitability

Workaround Available

MITRE ATT&CK

1 technique
Initial Access
View detailed technique mapping

References

https://access.redhat.com/security/cve/CVE-2026-9087
access.redhat.com
https://bugzilla.redhat.com/show_bug.cgi?id=2480172
bugzilla.redhat.com

Timeline

Published
May 20, 2026
Last Updated
May 20, 2026

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