CVE-2026-7571: Keycloak: keycloak: access token disclosure and implicit flow bypass via forged client data
A flaw was found in Keycloak. A low-privilege user, with knowledge of user credentials and client ID, can bypass a security control intended to disable the implicit flow in OpenID Connect (OIDC) clients. By manipulating client data during a session restart, an attacker can obtain an access token that should not be available. This vulnerability can also lead to the exposure of these access tokens in server logs, proxy logs, and HTTP Referrer headers, resulting in sensitive information disclosure.
Affected Software
Event History
Frequently Asked Questions
What is the severity of CVE-2026-7571?
CVE-2026-7571 has a low severity rating due to the requirement of low-privilege user access and knowledge of user credentials.
How does CVE-2026-7571 impact Keycloak users?
CVE-2026-7571 allows low-privilege users to bypass security controls designed to disable the implicit flow in OpenID Connect clients.
What versions of Keycloak are affected by CVE-2026-7571?
The vulnerability CVE-2026-7571 affects all versions of Keycloak that allow for the implicit flow in OpenID Connect clients.
How do I fix CVE-2026-7571?
To fix CVE-2026-7571, update your Keycloak instance to the latest version that addresses this vulnerability.
Is user authentication required to exploit CVE-2026-7571?
Yes, exploitation of CVE-2026-7571 requires knowledge of user credentials and the client ID.