XSS in Red Hat Build Of Keycloak
CVE-2026-9086
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.
Vulnerability class: XSS (Cross-Site Scripting)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 7.3 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:N.
EPSS exploit prediction
EPSS: 0.008 (54.3th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 54th percentile — 54.3% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.008 · newest: 0.008 · change: 0.000
Affected products
- Red Hat Build Of Keycloak
- Red Hat Build Of Keycloak 26.4 — versions 26.4.13-1, 26.4-19
- Red Hat Build Of Keycloak 26.4.13
- Red Hat Build Of Keycloak 26.6 — versions 26.6-8, 26.6.4-2
- Red Hat Build Of Keycloak 26.6.4
- Red Hat Build Of Keycloak
Weakness classification (CWE)
Public proof-of-concept exploits
References
- access.redhat.com/security/cve/CVE-2026-9086 (Third Party Advisory, vdb-entry)
- bugzilla.redhat.com/show_bug.cgi (issue-tracking, Third Party Advisory)
- access.redhat.com/errata/RHSA-2026:30083 (vendor-advisory, Third Party Advisory)
- access.redhat.com/errata/RHSA-2026:30084 (vendor-advisory, Third Party Advisory)
- access.redhat.com/errata/RHSA-2026:30049 (vendor-advisory, Third Party Advisory)
- access.redhat.com/errata/RHSA-2026:30050 (vendor-advisory, Third Party Advisory)
- 0b0ca135-0b70-47e7-9f44-1890c2a1c46c (Third Party Advisory)
Frequently asked questions
- What is CVE-2026-9086?
- CVE-2026-9086 is a high-severity vulnerability in Red Hat Build Of Keycloak, classified under Cross-site Scripting. CVSS score: 7.3/10. Published 2026-06-25.
- How severe is CVE-2026-9086?
- High severity. CVSS v3 base score is 7.3 out of 10.
- Is CVE-2026-9086 known to be exploited?
- 1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.