CVE-2026-19607 Keycloak-services: keycloak-services: broker-originated username collision causes account lockout
Attackers can lock out legitimate users by registering a colliding username on an external identity provider, disrupting access to Keycloak accounts.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-19607?
CVE-2026-19607 is a medium-severity authentication bypass vulnerability in Red Hat Single Sign-On 7, published on 16 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
A flaw was found in the first-broker-login flow of the keycloak-services component. This component handles the initial authentication and account linking when a user logs in via an external identity provider. The issue allows an attacker to register a matching username on an external provider to trigger a collision in Keycloak, which results in the legitimate user being locked out of their account.
Weakness: CWE-287
Which versions are affected by CVE-2026-19607?
How do I fix CVE-2026-19607?
No fix has been published for CVE-2026-19607 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-2026-19607 being exploited?
There is no known exploitation of CVE-2026-19607 in the wild and no public exploit code.
Public exploit code: 1 proofs of concept on GitHub.
Sources
Also known as GHSA-h87q-rx56-87wm, UBUNTU-CVE-2026-19607.