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Description

A flaw was found in Keycloak, an open-source identity and access management solution. When a user account is temporarily locked due to repeated failed login attempts, an attacker with valid client credentials can exploit the Client-Initiated Backchannel Authentication (CIBA) flow to bypass this brute-force protection. This allows continued authentication attempts and token issuance even when the account should be locked, potentially enabling further unauthorized access attempts.

PUBLISHED Reserved 2026-05-28 | Published 2026-05-28 | Updated 2026-05-29 | Assigner redhat




MEDIUM: 4.3CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N

Problem types

Authentication Bypass by Primary Weakness

Product status

Default status
affected

Timeline

2026-05-28:Reported to Red Hat.
2026-05-28:Made public.

Credits

Red Hat would like to thank Evan Hendra (Independent Security Researcher) for reporting this issue.

References

access.redhat.com/security/cve/CVE-2026-9798 vdb-entry

bugzilla.redhat.com/show_bug.cgi?id=2482470 (RHBZ#2482470) issue-tracking

cve.org (CVE-2026-9798)

nvd.nist.gov (CVE-2026-9798)

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