Running a vulnerability scanner often gives you a long list of findings. Many are low-priority noise, but a few high/critical issues appear again and again in real environments and they keep causing breaches year after year.
Here are the most common, most dangerous, and most preventable results that keep showing up in actual scans of home networks, small businesses, homelabs, and mid-size organizations in recent years.
1. Outdated / End-of-Life Software & OS
Typical finding
1. Microsoft Windows Server 2012 R2 / Windows 7 / Windows 8.1 (end-of-support)
2. Apache 2.4.29–2.4.38 (multiple CVEs)
3. PHP 7.4.x or older
4. Adobe Flash Player remnants (yes, still found in 2025)
Real example: A small accounting firm scanned their file server → OpenVAS flagged Windows Server 2012 R2 with CVE-2020-1472 (Zerologon) and multiple unpatched remote code execution flaws. They delayed patching → attacker exploited Zerologon → gained domain admin → deployed ransomware → $180,000 ransom demand + 4 weeks downtime.
Lesson: Anything end-of-life should be replaced or isolated immediately. No patch = no defense.
2. Remote Desktop / RDP on an Exposed Port (3389)
Typical finding
1. Port 3389 is publicly available via the Internet (CVSS 9.8 if NLA not required)
2. Default or weak user account credentials
3. No network level authentication (NLA) in use
Real example: A home user with a small e-commerce business exposed RDP to their NAS/server; OpenVAS rated it a critical security finding. They ignored the finding; An attacker was able to brute force a weak password; The attacker installed a cryptominer and credential theft tool; The attacker stole $12,000 from the linked PayPal account.
Lesson: You should not expose RDP directly to the Internet. Use a VPN, jump host, or Azure Bastion / AWS Systems Manager for remote access.
3. Weak / Default Credentials on Network Devices
Typical finding
1. Router / NAS / IP camera / printer with default admin password (admin/admin, admin/password, root:xc3511, etc.)
2. CVSS 9.8–10.0 if internet-facing
Real example: An actual case occurred when an unprotected dental office was compromised by a QNAP Network Attached Storage Device (NAS) that had the default root password. The NAS was found to be exposed through a port scan on port 443. The attacker accessed the NAS, encrypted the entire contents of the patient record database (including all patient images), and demanded a ransom of $35,000 for the decryption key. After paying half of the ransom, the dental office recovered some of their data.
Lesson: changing any default passwords to strong, unique passwords using a password manager and turning off remote access from the Internet unless necessary.
4. E-commerce websites can be a great source of income, however if they are not maintained properly, they can be at risk of abuse.
Common issue
1. Outdated plugins for WordPress (i.e. Elementor and WP File Manager).
2. Joomla and Drupal with known CVEs (Common Vulnerabilities).
3. Publicly exposed versions of phpMyAdmin.
Real example: local bakery operates an e-commerce website on WordPress that uses an outdated file-upload plugin. Through traditional tools such as Nuclei and OpenVAS, when examined for security compliance against the CVE-2021-29447, it was confirmed the backend of WordPress was vulnerable to attackers who uploaded webshells to access and subsequently manipulates the original install. Consequently, the bakery lost several weeks of online orders when their hosting provider suspended their account due to a continued breach.
Lesson: should include uniformly updating all CMSs and their supporting applications through automatic notifications, including themes and plug-ins. In addition, remove plugins that have no current use. Do not expose phpMyAdmin or administrator portals to the Internet.
5. Missing Multi-Factor Authentication
Common issue
1. Accounts are secured using weak passwords and MFA is not enabled on accounts that require access via RDP, VPN, email (Office 365/G-Suite) and Cloud console.
2. When Weak Password and No MFA are both present, the score is often rated as 8.09 - 9.79 in CVSS.
Real example: freelance graphic designer using their own Gmail account for all client to complete invoicing. No MFA was on their account and the result of a password spray removed access to over 100 emails sent to clients requesting payments. This resulted in designer being victim of fraud by losing approximately $8000 in payments made by fraudsters.
Lesson: is to enable MFA wherever possible. Most importantly for email, cloud consulates, VPN, banking and cryptocurrency accounts. Best practice is to use App or Hardware Key. Doing so, is more secure than using SMS verification.
Practical Tools to Find & Learn from These Issues
1. OpenVAS / Greenbone Community Edition (free) Run a full scan → focus on CVSS ≥ 7.0 → export PDF report → fix one critical finding per week.
2. Nuclei (fast, template-based scanner)
nuclei -u https://your-site.com -t cves/ -severity critical,high
3. Nmap with vulners script (quick check)
nmap -sV --script vulners 192.168.1.0/24
4. Microsoft Defender Vulnerability Management (free for many Microsoft 365 licenses) Gives prioritized list of exploitable issues on Windows endpoints.
5. Have I Been Pwned? (free) Check if your email or passwords already leaked → change them immediately.
Key Takeaways
These five issues (outdated OS/software, exposed RDP, default credentials, unpatched web apps, no MFA) appear in almost every real scan and keep causing real money loss and downtime.
You don’t need to be a security expert, just run a free scanner once, fix the red/high/critical items first, and repeat every few months. Most breaches start with one of these preventable mistakes.
