What is CVE-2026-16103?

CVE-2026-16103 is a medium-severity vulnerability in Red Hat Build Of Keycloak, classified under Authentication Bypass by Primary Weakness. CVSS score: 4.3/10. Published 2026-07-17.

How severe is CVE-2026-16103?

Medium severity. CVSS v3 base score is 4.3 out of 10.

Vulnerability in Red Hat Build Of Keycloak

CVE-2026-16103

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.

EPSS: 0.003 (26.9th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 4.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N.

Affected products

Weakness classification (CWE)

References

secalert@redhat.com (x_refsource_REDHAT, vdb-entry, Vendor Advisory)
secalert@redhat.com (x_refsource_REDHAT, issue-tracking, Issue Tracking, Vendor Advisory)

Frequently asked questions

What is CVE-2026-16103?: CVE-2026-16103 is a medium-severity vulnerability in Red Hat Build Of Keycloak, classified under Authentication Bypass by Primary Weakness. CVSS score: 4.3/10. Published 2026-07-17.
How severe is CVE-2026-16103?: Medium severity. CVSS v3 base score is 4.3 out of 10.