CVEvulnerability

CVE-2026-18209

4.7 MEDIUM Published 2026-07-31 Modified 2026-09-16 Official page ↗
Status
Modified
Published
2026-07-31
Last modified
2026-09-16
Assigner
[email protected]
CVSS 3.1 ([email protected])
3.4 LOW — CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:N/I:L/A:N
CVSS 3.1 ([email protected])
4.7 MEDIUM — CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:N/I:L/A:N
Weaknesses
CWE-1288

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 configurations

• redhat build of keycloak

Related

Weakness · CWE (1)

  • CWE-1288 Improper Validation of Consistency within Input weakness

References