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External Control of Assumed-Immutable Web Parameter

CVE-2026-7571

High
7.1/10

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 versions are prior to 26.6.2.

  • LOW
  • NETWORK
  • LOW
  • UNCHANGED
  • NONE
  • LOW
  • HIGH
  • NONE

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

The web application does not sufficiently verify inputs that are assumed to be immutable but are actually externally controllable, such as hidden form fields.

References

Advisory Timeline

  • Published