CVE-2026-7571

Summary

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

VendorProductVersion RangeStatus
Red HatRed Hat build of Keycloak 26.426.4.12-1 < *unaffected
Red HatRed Hat build of Keycloak 26.426.4-17 < *unaffected
Red HatRed Hat build of Keycloak 26.426.4-17 < *unaffected

Weaknesses

  • CWE-472: External Control of Assumed-Immutable Web Parameter

Workarounds

To mitigate this issue, restrict network access to the Keycloak authentication endpoint to trusted clients and networks. Implement firewall rules to control inbound connections to the Keycloak service ports, thereby reducing the attack surface and limiting who can initiate authentication flows and potentially exploit the implicit flow bypass. If the Keycloak service is reloaded or restarted, ensure these network restrictions remain in effect.

ADP Enrichment

CISA ADP Vulnrichment

  • SSVC:
  • Exploitation: none
    • Automatable: no
    • Technical Impact: partial

References