CVE-2026-9086

Estado: AnalizadaAlta (7.3)—

A flaw was found in Keycloak. A remote attacker with administrative privileges, specifically those with `manage-client` permission or access to client registration endpoints, could bypass client Uniform Resource Identifier (URI) validation. This is achieved by registering a malicious client with a specially crafted redirect URI using a case-insensitive `javascript:` or `data:` scheme. This Cross-Site Scripting (XSS) vulnerability allows for arbitrary code execution in the Keycloak origin when a victim clicks the crafted link, such as in the logout flow or the Admin Console.

CVSS

Versión: 3.1
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:N
Puntuación base: 7.3

Probabilidad de explotación (EPSS)

Probabilidad de explotación en los próximos 30 días: 0.78%
Percentil entre todas las CVEs puntuadas: 54
Fecha de la puntuación: 5/10/2026

EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).

🎯 Técnicas ATT&CK

Cómo se explota esta vulnerabilidad y qué consigue el atacante, en el lenguaje de MITRE ATT&CK.

ExplotaciónT1189 Drive-by Compromiseinitial access95 %
Impacto principalT1059.007 JavaScriptexecution90 %
Impacto secundarioT1078 Valid Accountsstealth · persistence · privilege escalation · initial access75 %

XSS mediante redirect URI malicioso (javascript:/data:) en cliente Keycloak: ataque drive-by (T1189). Ejecución de código JavaScript arbitrario en origen Keycloak (T1059.007). Requiere privilegios administrativos (manage-client) para registrar cliente malicioso, comprometiendo sesiones de víctimas.

Inferido por nuestro agente de análisis a partir de la descripción oficial, el vector CVSS y la CWE, y comprobado por un supervisor. Puede contener errores.

🛡️ Mitigaciones ATT&CK que cubren estas técnicas

User Training Restrict Web-Based Content Application Developer Guidance Active Directory Configuration User Account Management Privileged Account Management

Tecnologías afectadas (1)

Redhat — Build OF Keycloak

CWE

CWE-79
CWE-79

Referencias

JSON original (NVD)

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