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CVE PROGRAM SOURCE RECORD3.4 Low

CVE-2026-18209

Keycloak-services: keycloak-services: oidc redirect_uri fragment bypass in http parameter pollution check

Description

A flaw was found in the keycloak-services component of Keycloak, which handles OpenID Connect (OIDC) authentication flows. The issue occurs because the security check designed to prevent HTTP parameter pollution only inspects the query portion of a redirect URL and ignores the fragment portion. When a client is configured with a wildcard redirect URI, an attacker can use this to inject duplicate security parameters into the login response. If a client application is not configured correctly, it might trust the attacker's injected data instead of the real security information from Keycloak, leading to session fixation or account confusion.

Affected products

Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.

Red Hat Red Hat build of Keycloak 26.6

Default version status: affected

  • 26.6.7-3 to < *unaffected

Red Hat Red Hat build of Keycloak 26.6

Default version status: affected

  • 26.6-20 to < *unaffected

Red Hat Red Hat build of Keycloak 26.6

Default version status: affected

  • 26.6-20 to < *unaffected

Red Hat Red Hat build of Keycloak 26.6.7

Default version status: unaffected

Red Hat Red Hat build of Keycloak 26.6.7

Default version status: unaffected

Red Hat Red Hat build of Keycloak 26.6.7

Default version status: unaffected

Red Hat Red Hat Data Grid 8

Default version status: unaffected

Red Hat Red Hat JBoss Enterprise Application Platform Expansion Pack

Default version status: unaffected

Red Hat Red Hat Single Sign-On 7

Default version status: unaffected

References