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Fencer Vulns
high 7.3

CVE-2026-9086 json

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

published 2026-06-25 4 mo ago modified 2026-10-29 10 d ago also BIT-keycloak-2026-9086 , EUVD-2026-39473 , GHSA-v3f7-2p4r-mwfw

cvss
7.3
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.8%
EPSS 0.8% chance of exploitation in 30 days, percentile 56%
public exploits
0
none known

Summary

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.

Patch / fix

  • maven org.keycloak:keycloak-services 26.6.4
  • bitnami keycloak 26.4.13, 26.6.4
  • Red Hat Red Hat build of Keycloak 26.4 26.4-19, 26.4.13-1
  • Red Hat Red Hat build of Keycloak 26.6 26.6-8, 26.6.4-2

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-9086 updated cvss 7.3

keycloak: Keycloak: Cross-site scripting (XSS) via case-insensitive URI validation bypass

  • Red Hat build of Keycloak 26.4 rhbk/keycloak-rhel9 26.4-19, rhbk/keycloak-rhel9-operator 26.4-19, rhbk/keycloak-operator-bundle 26.4.13-1
    fixed: vendor fix RHSA-2026:30050
  • Red Hat build of Keycloak 26.4.13
    fixed: vendor fix RHSA-2026:30049
  • Red Hat build of Keycloak 26.6 rhbk/keycloak-rhel9 26.6-8, rhbk/keycloak-rhel9-operator 26.6-8, rhbk/keycloak-operator-bundle 26.6.4-2
    fixed: vendor fix RHSA-2026:30084
  • Red Hat build of Keycloak 26.6.4
    fixed: vendor fix RHSA-2026:30083

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
total
Assessed
4 mo ago

Exploit prediction

0.78% chance of exploitation in the next 30 days, higher than 56% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 7.3 CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:N
CISA ADP 3.1 7.3 CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:N
GitHub 3.1 7.3 CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:N
OSV 3.1 7.3 CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:N

Affected packages

ecosystem package affected fixed in
maven org.keycloak:keycloak-services
<26.6.4
26.6.4
bitnami keycloak
>=26.4.0, <26.4.13
>=26.6.0, <26.6.4
26.4.13
26.6.4

Affected products

  • Red Hat Red Hat build of Keycloak 26.4
  • Red Hat Red Hat build of Keycloak 26.4.13
  • Red Hat Red Hat build of Keycloak 26.6
  • Red Hat Red Hat build of Keycloak 26.6.4

Classification

Weakness
  • CWE-79 Improper Neutralization of Input During Web Page Generation

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.