CVE-2026-9689 PUBLISHED

Keycloak: org.keycloak.protocol.oidc: http parameter pollution in oidc redirect uri allows response parameter duplication - #ghi-604

Assigner: redhat
Reserved: 27.05.2026 Published: 27.05.2026 Updated: 27.05.2026

A flaw was found in Keycloak, an open-source identity and access management solution. When a client application is configured to accept broad redirect Uniform Resource Identifiers (URIs), a remote attacker can manipulate the authentication process by crafting a special web address. If a user clicks this link, the client application might incorrectly prioritize attacker-controlled information over legitimate data. This vulnerability, known as HTTP parameter pollution, could allow an attacker to bypass security measures or gain unauthorized access to resources.

Metrics

CVSS Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:N
CVSS Score: 4.2

Product Status

Vendor Red Hat
Product Red Hat Build of Keycloak
Versions Default: affected

Credits

  • Red Hat would like to thank Martin Bartoš for reporting this issue.

References

Problem Types

  • Improper Validation of Consistency within Input CWE