id: CVE-2021-20323
info:
name: Keycloak 10.0.0 - 18.0.0 - Cross-Site Scripting
author: ndmalc
severity: medium
description: |
Keycloak 10.0.0 to 18.0.0 contains a cross-site scripting vulnerability via the client-registrations endpoint. On a POST request, the application does not sanitize an unknown attribute name before including it in the error response with a 'Content-Type' of text/hml. Once reflected, the response is interpreted as HTML. This can be performed on any realm present on the Keycloak instance. Since the bug requires Content-Type application/json and is submitted via a POST, there is no common path to exploit that has a user impact.
remediation: |
Upgrade Keycloak to a version that is not affected by the vulnerability (10.0.1 or higher).
reference:
- https://github.com/keycloak/keycloak/security/advisories/GHSA-m98g-63qj-fp8j
- https://bugzilla.redhat.com/show_bug.cgi?id=2013577
- https://access.redhat.com/security/cve/CVE-2021-20323
- https://github.com/ndmalc/CVE-2021-20323
- https://github.com/keycloak/keycloak/commit/3aa3db16eac9b9ed8c5335ac86f5f50e0c68662d
- https://nvd.nist.gov/vuln/detail/CVE-2021-20323
classification:
cvss-metrics: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
cvss-score: 6.1
cve-id: CVE-2021-20323
cwe-id: CWE-79
epss-score: 0.00198
epss-percentile: 0.57535
cpe: cpe:2.3:a:redhat:keycloak:*:*:*:*:*:*:*:*
metadata:
verified: true
max-request: 4
vendor: redhat
product: keycloak
shodan-query: html:"Keycloak"
tags: cve,cve2021,keycloak,xss
http:
- method: POST
path:
- "{{BaseURL}}/auth/realms/master/clients-registrations/default"
- "{{BaseURL}}/auth/realms/master/clients-registrations/openid-connect"
- "{{BaseURL}}/realms/master/clients-registrations/default"
- "{{BaseURL}}/realms/master/clients-registrations/openid-connect"
body: "{\"Test\":1}"
stop-at-first-match: true
headers:
Content-Type: application/json
matchers-condition: and
matchers:
- type: word
part: body
words:
- 'Unrecognized field "Test'
- type: word
part: header
words:
- text/html
- type: status
status:
- 400
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