CVE-2026-9086
Keycloak: keycloak: cross-site scripting (xss) via case-insensitive uri validation bypass
HIGH 7.3EPSS 0.8%
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.
- Affected
- Red Hat · Red Hat build of Keycloak 26.4 · Red Hat build of Keycloak 26.4.13 · Red Hat build of Keycloak 26.6 · Red Hat build of Keycloak 26.6.4
- CVSS v3.1 CNA
- 7.3 HIGH
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:N - EPSS
- 0.78% chance of exploitation in the next 30 days, 55th percentile
- Published
- 2026-06-25
- Updated
- 2026-07-15
Proof-of-concept exploits (1)
- Saku0512/CVE-2026-9086-poc1★ · 2026-08-10
Security advisories
- https://access.redhat.com/errata/RHSA-2026:30049
- https://access.redhat.com/errata/RHSA-2026:30050
- https://access.redhat.com/errata/RHSA-2026:30083
- https://access.redhat.com/errata/RHSA-2026:30084
- https://access.redhat.com/security/cve/CVE-2026-9086
- https://bugzilla.redhat.com/show_bug.cgi?id=2480170
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-9086.json