CVE-2026-16103 Keycloak-services: keycloak-services: incomplete fix for ciba brute-force lockout bypass at token redemption
Attackers can bypass brute-force lockouts to obtain tokens for locked accounts if authentication was initiated before the lockout, requiring valid client credentials.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- None listed
What is CVE-2026-16103?
CVE-2026-16103 is a medium-severity authentication bypass vulnerability in Redhat Build of Keycloak, published on 17 Jul 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official 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.
Which versions are affected by CVE-2026-16103?
It affects 1 product.
Products include Redhat Build of Keycloak.
How do I fix CVE-2026-16103?
No fix has been published for CVE-2026-16103 yet. Limit exposure of the affected software until one is available.
Upgrade, and rotate credentials and sessions that may have been exposed. More about Authentication bypass.
Is CVE-2026-16103 being exploited?
There is no known exploitation of CVE-2026-16103 in the wild and no public exploit code.
Other vulnerabilities in Redhat Build of Keycloak
- CVE-2026-15572 Keycloak-services: keycloak-services: dcr protocol mapper type-swap policy bypass allows privilege escalation
- CVE-2026-3047 Keycloak SAML Broken has Authentication Bypass by Primary Weakness
- CVE-2026-15573 Keycloak-services: keycloak-services: authorization bypass via unnormalized uri matching in pathmatcher
- CVE-2026-16102 Keycloak-services: keycloak-services: default dcr policy allows role forgery via user property mappers
- CVE-2026-1609 Org.keycloak/keycloak-quarkus-server: keycloak: unauthorized access via jwt authorization grant with disabled users
Sources
Also known as GHSA-v7m3-vpqr-6m6p.