CVE-2026-7571: Keycloak: keycloak: access token disclosure and implicit flow bypass via forged client data

Severity: high (CVSS 7.1 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.4% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-05-19 · updated 2026-10-26
Weakness: CWE-472

Description

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 products

Red Hat build of Keycloak 26.4: from 26.4 before 26.4.12 — fixed in 26.4.12

How to fix

Upgrade to a fixed version: Red Hat build of Keycloak 26.4 26.4.12. Check the vendor advisory for mitigations.

References

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