CVE-2026-16103 — MEDIUM (4.3)

Vulnerability Description

A flaw was found in the keycloak-services component of Keycloak. This issue is an incomplete fix for CVE-2026-9798, where brute-force protection checks were added to the Client-Initiated Backchannel Authentication (CIBA) initiation handler but were omitted from the token redemption handler. This allows an attacker with valid client credentials to obtain access and refresh tokens for a user account that has been locked due to brute-force protection, provided the authentication request was started before the lockout occurred and was approved by the user.

CVSS Score

4.3

MEDIUM

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

Attack Vector

NETWORK

Attack Complexity

LOW

Privileges Required

NONE

User Interaction

REQUIRED

Scope

UNCHANGED

Confidentiality

LOW

Integrity

NONE

Availability

NONE

Affected Products

Vendor	Product	Versions
Redhat	Build Of Keycloak	-

Related Weaknesses (CWE)

CWE-841

References

https://access.redhat.com/security/cve/CVE-2026-16103Vendor Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=2501736Issue TrackingVendor Advisory

FAQ

What is CVE-2026-16103?

CVE-2026-16103 is a vulnerability with a CVSS score of 4.3 (MEDIUM). A flaw was found in the keycloak-services component of Keycloak. This issue is an incomplete fix for CVE-2026-9798, where brute-force protection checks were added to the Client-Initiated Backchannel A...

How severe is CVE-2026-16103?

CVE-2026-16103 has been rated MEDIUM with a CVSS base score of 4.3/10. Review the CVSS metrics above for detailed severity breakdown.

Is there a patch for CVE-2026-16103?

Check the references section above for vendor advisories and patch information. Affected products include: Redhat Build Of Keycloak.