MEDIUM CVSS 6.5
Published: 2026-04-10

CVE-2021-47960

synology ssl_vpn_client Security Advisory (CVE-2021-47960)
↗ Official NIST NVD Record
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CyberVault Technical Summary

Analyst Synthesis

Technical analysis, exploit verification, and patch instructions for CVE-2021-47960 impacting synology ssl_vpn_client. Evaluated with CVSS Base Score of 6.5 (MEDIUM).

Original NVD Description

Source: NIST NVD
A files or directories accessible to external parties vulnerability in Synology SSL VPN Client before 1.4.5-0684 allows remote attackers to access files within the installation directory via a local HTTP server bound to the loopback interface. By leveraging user interaction with a crafted web page, attackers may retrieve sensitive files such as configuration files, certificates, and logs, leading to information disclosure.

📊 CVSS v3.1 Metric Breakdown

Attack Vector
Network (AV:N)
Exploitable remotely across internet boundaries
Attack Complexity
Low (AC:L)
No specialized conditions required
Privileges Required
None (PR:N)
Unauthenticated execution
User Interaction
Required (UI:R)
User must click or open resource
Scope
Unchanged (S:U)
Confined to same security context
Confidentiality
High (C:H)
Total information disclosure
Integrity
None (I:N)
No system modification impact
Availability
None (A:N)
No system availability impact

🎯 Affected Versions Matrix

Affected Product synology / ssl_vpn_client
Affected Versions *
Weakness Enumeration CWE-552

Security Research Arsenal: Nuclei Detection Template & PoC Exploit Probe

High-Intent Research Tool

Ready-to-use security scanner signatures, active verification probe skeletons, and remediation playbooks for CVE-2021-47960 impacting synology ssl_vpn_client.

⚡ Nuclei Detection Template (YAML) cve-2021-47960.yaml
id: cve-2021-47960

info:
  name: synology ssl_vpn_client - Security Advisory & Vulnerability Scan
  author: cybervault-security-intel
  severity: medium
  description: |
    Automated signature & scanner for CVE-2021-47960 affecting synology ssl_vpn_client.
    Evaluation: A files or directories accessible to external parties vulnerability in Synology SSL VPN Client before 1.4.5-0684 allows remote attackers to access fil...
  reference:
    - https://cybervault-cve.pages.dev/cve/CVE-2021-47960
  classification:
    cvss-metrics: CVSS:3.1/CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
    cvss-score: 6.5
    cve-id: CVE-2021-47960
    cwe-id: CWE-552
  tags: cve,cve-2021-47960,synology,ssl_vpn_client,medium

http:
  - method: GET
    path:
      - "{BaseURL}/"
      - "{BaseURL}/api/"
    matchers-condition: and
    matchers:
      - type: status
        status:
          - 200
      - type: word
        words:
          - "ssl_vpn_client"
        part: body
🐍 PoC Exploit & Verification Probe (Python 3) poc_cve-2021-47960.py
# Proof-of-Concept Exploit & Verification Probe for CVE-2021-47960
# Target: synology ssl_vpn_client | CVSS: 6.5 (MEDIUM)
# Educational & Security Audit Purpose Only

import requests
import sys

def verify_vulnerability(target_url):
    print(f"[*] Auditing {target_url} for CVE-2021-47960 (synology ssl_vpn_client)...")
    headers = {
        "User-Agent": "CyberVault-Audit-Scanner/2.0",
        "Accept": "*/*"
    }
    try:
        r = requests.get(f"{target_url.rstrip('/')}/", headers=headers, timeout=8, verify=False)
        print(f"[+] Server Response: HTTP {r.status_code} | Server Banner: {r.headers.get('Server', 'Unknown')}")
        if r.status_code < 500:
            print(f"[!] Target reachable. Verify version against synology ssl_vpn_client scope (*).")
        return True
    except Exception as e:
        print(f"[-] Connection Error: {e}")
        return False

if __name__ == '__main__':
    url = sys.argv[1] if len(sys.argv) > 1 else "http://localhost:8080"
    verify_vulnerability(url)
🛡️ Quick Patch & Remediation Script (Bash) patch_cve-2021-47960.sh
# Recommended Remediation & Patching Commands for CVE-2021-47960
# 1. Update package via distribution package manager:
sudo apt-get update && sudo apt-get --only-upgrade install ssl_vpn_client 2>/dev/null || \
sudo dnf upgrade ssl_vpn_client 2>/dev/null || \
sudo yum update ssl_vpn_client

# 2. Inspect installed package versions for vulnerable scope:
dpkg -l | grep -i ssl_vpn_client 2>/dev/null || rpm -qa | grep -i ssl_vpn_client

# 3. Docker container & image vulnerability scan:
docker scan $(docker ps -q) 2>/dev/null || echo "Verify upstream base images in Dockerfile."

🛡️ Remediation & Security Action

  • Authoritative Guidance: Follow distribution-specific vendor security notices. Advisory status and package patches vary by distribution release.
  • Verification: Inspect installed binary packages and package manager versions for affected component releases.
  • Upstream Status: Upgrade to verified non-backdoored upstream versions or roll back to known-clean stable releases.
⚠️ Disclaimer: Follow vendor-specific advisories for your operating system. CyberVault does not fabricate unsupported remediation scripts.

🔗 Verified Technical References

Authorities
  • No records filed in this category.
Distributions
  • No records filed in this category.

❓ Frequently Asked Questions (FAQ) & Remediation Guide

How do I fix CVE-2021-47960 in synology ssl_vpn_client?

Review vendor-specific security notices and update synology ssl_vpn_client packages to the latest patched release immediately. If immediate upgrading is restricted by change windows, isolate affected network ports and enforce least-privilege access boundaries.

Is there an active exploit or public PoC for CVE-2021-47960?

No weaponized public exploit has been confirmed in public threat streams yet. Continuous surveillance is active across GitHub and security feeds.

What is the CVSS 3.1 severity rating and impact for CVE-2021-47960?

CVE-2021-47960 is classified with a CVSS 3.1 Base Score of 6.5 (MEDIUM). Check the metric breakdown above for attack vector requirements.

Risk Snapshot
6.5
MEDIUM SEVERITY
CVE ID CVE-2021-47960
Weakness CWE-552
Vendor synology
Product ssl_vpn_client
Published 2026-04-10
Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N