CVE-2026-9086

Keycloak: keycloak: cross-site scripting (xss) via case-insensitive uri validation bypass

HIGH
7.3
CVSS Score
Published: June 25, 2026 at 04:16 PM UTC
Updated: July 15, 2026 at 01:17 AM UTC
1 product affected across 1 vendorBuild of Keycloak

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Severity
HIGH7.3
Exploit prediction
EPSS 0.8%
SSVC
No known exploit

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

26.4 ≤ v < 26.4.1326.6 ≤ v < 26.6.4
Vendor states this is fixed in 26.4-19 (unaffected)
Vendor states this is fixed in 26.4.13 (unaffected)
Vendor states this is fixed in 26.4.13-1 (unaffected)
Vendor states this is fixed in 26.6-8 (unaffected)
Vendor states this is fixed in 26.6.4 (unaffected)
Vendor states this is fixed in 26.6.4-2 (unaffected)

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

References (7)

VDB Entryx_refsource_REDHATThird Party Advisory
Source: cverecord
https://access.redhat.com/security/cve/CVE-2026-9086
Issue Trackingx_refsource_REDHATThird Party Advisory
Source: cverecord
https://bugzilla.redhat.com/show_bug.cgi?id=2480170
Vendor Advisoryx_refsource_REDHATThird Party Advisory
Source: cverecord
https://access.redhat.com/errata/RHSA-2026:30083
Vendor Advisoryx_refsource_REDHATThird Party Advisory
Source: cverecord
https://access.redhat.com/errata/RHSA-2026:30084
Vendor Advisoryx_refsource_REDHATThird Party Advisory
Source: cverecord
https://access.redhat.com/errata/RHSA-2026:30049
Vendor Advisoryx_refsource_REDHATThird Party Advisory
Source: cverecord
https://access.redhat.com/errata/RHSA-2026:30050
Third Party Advisory
Source: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-9086.json

SSVC — Action Prioritization

SSVCNo known exploitNot automatableTotal impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

7.3HIGHredhat
Attack Vector
NETWORK
Complexity
LOW
Privileges
LOW
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
HIGH
Availability
NONE
Vector?

Quick Info

StatusANALYZED
CWE
CWE-79

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