Keycloak vulnerable to cross-site scripting (xss) via case-insensitive uri validation bypass

高 7.3CVE-2026-9086 · BIT-keycloak-2026-9086 · GHSA-v3f7-2p4r-mwfw · 25/06/2026 公開 · 15/07/2026 更新

要点

CVE-2026-9086 は org.keycloak:keycloak-services, build of keycloak (redhat) に影響する深刻度「高」 (CVSS 7.3) の脆弱性です。
今後30日間に悪用される確率（EPSS）：0.78%（全脆弱性の 56.0% より高い）。
対処：26.6.4, 26.4.13 以降に更新してください。

パッケージ	影響を受けるバージョン	修正済みバージョン
org.keycloak:keycloak-services Maven	`< 26.6.4`	`26.6.4`
build of keycloak redhat	`≥ 26.4, < 26.4.13≥ 26.6, < 26.6.4`	`26.4.1326.6.4`

概要

Description

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.

NVD の説明

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.