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Medium · 4.2 CVE-2026-9689 EUVD-2026-32212GHSA-wcvj-vpvw-9rr5

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

Published May 27, 2026 · Updated Aug 20, 2026 · Assigned by redhat

Description

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.

Affected products

VendorProductAffectedFixed
Red Hat Red Hat build of Keycloak 26.4 — —
Red Hat Red Hat build of Keycloak 26.4.14 — —
Red Hat Red Hat build of Keycloak 26.6 — —
Red Hat Red Hat build of Keycloak 26.6.5 — —

Fixed in Linux distributions

Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.

Wolfi

ReleasePackageFixed inAdvisory
Wolfi rolling keycloak-26.5 +2 No fix yet —
Wolfi rolling keycloak-26.6 +1 26.6.6-r0 —

Affected packages

EcosystemPackageAffectedFixedRecord
Maven org.keycloak:keycloak-services >= 26.5.0, <= 26.6.4 — GHSA-wcvj-vpvw-9rr5
Maven org.keycloak:keycloak-services <= 26.4.7 — GHSA-wcvj-vpvw-9rr5

Advisories 1

References