How to Read a Security Scan Result When You're Not a Security Expert

You ran your first external security scan. Now you're staring at 200 findings, a column of CVSS scores, and severity labels that seem to say everything is critical. This guide tells you what those results actually mean, and, more importantly, what to do next.

The first time most people run an external security scan, the results are simultaneously overwhelming and confusing. There are hundreds of findings. Everything seems to be labelled CRITICAL or HIGH. There are CVE numbers, CVSS scores, port numbers, and technical descriptions that read like a foreign language. And somewhere in the back of your mind is the question: is my company actually on fire right now, or is this just how security tools always look?

The honest answer is: it is usually somewhere in between. Security scans surface real issues, but most of them are not the kind that will cause a breach this afternoon. The skill is learning which ones to take seriously immediately, which ones to schedule, and which ones to understand but not panic about.

This guide explains exactly that, in plain English, without assuming you have a background in security.

What a Security Scan Is Actually Doing

An external security scan looks at your organisation the way an attacker would: from the outside, using only information that is publicly accessible on the internet. It identifies all your internet-facing assets, websites, subdomains, APIs, cloud resources, mail servers, and checks each one for known vulnerabilities, misconfigurations, and exposures.

The important word is external. An external scan cannot see inside your network, your internal systems, or your databases. What it sees is everything that is visible from the internet, which is often more than most organisations expect, and it is exactly what an attacker sees before they decide whether your organisation is worth targeting.

Understanding Severity Ratings

Most security scan results use a four-level severity system: Critical, High, Medium, and Low. Here is what each level actually means in plain terms:

Critical

A Critical finding means there is a known vulnerability that an attacker could exploit relatively easily, right now, with publicly available tools, and the impact of successful exploitation would be severe (access to sensitive data, ability to run code on your systems, complete system compromise).

What to do: Treat these as the security equivalent of a gas leak. Stop what you are doing and address these within 24 to 72 hours. If you cannot fix them immediately, at minimum take the affected system offline or restrict access to it while you work on a fix.

High

A High finding is serious but typically requires some additional conditions to be exploitable, a specific configuration, a particular version, or access to something else on the system. The impact is still significant.

What to do: Address within one to two weeks. These belong on a prioritised remediation list and should be tracked until resolved.

Medium

A Medium finding is a real issue that could contribute to a security incident, often by making an attacker's job easier or by creating a pathway that, combined with another finding, could be exploited. On its own, it is unlikely to lead directly to a breach.

What to do: Schedule these for resolution within 30 days. They matter, but they should not displace Critical and High work.

Low

A Low finding is typically a configuration that follows best practices less well than ideal, or a disclosure of information that an attacker could potentially use to plan a more targeted attack. It is not an active threat on its own.

What to do: Track these and address them during maintenance windows. Do not let Low findings distract from Critical and High work.

The number trap: It is tempting to measure your security progress by the total number of findings. This is misleading. Ten findings, two of which are Critical, is a more dangerous situation than 150 findings, none of which are Critical. Always look at severity distribution first, not total count.

What is a CVSS Score?

CVSS stands for Common Vulnerability Scoring System. It is a standardised way of rating the severity of specific vulnerabilities, each score is a number from 0 to 10, where higher numbers indicate more severe vulnerabilities. You will see these associated with specific vulnerabilities that have a CVE number (a Common Vulnerabilities and Exposures identifier, which is essentially a unique ID for a known security flaw).

Here is the CVSS scale in plain terms:

An important caveat: CVSS scores are theoretical severity ratings calculated in isolation. A CVSS 9.8 vulnerability that affects software you do not use is less dangerous than a CVSS 6.5 vulnerability in software that sits directly in front of your customer database. Context always matters more than the score alone.

Understanding What the Findings Are Telling You

Security scan findings typically fall into a few categories. Here is what each type actually means:

Open Ports

Ports are essentially numbered doorways on a server that allow different types of network traffic. An "open port" finding means a port is accessible from the internet that may not need to be. Common findings: port 22 (SSH, remote access), port 3389 (RDP, Windows remote desktop), port 8080/8443 (often web applications in development or admin interfaces).

What to do: Ask your IT team or hosting provider whether each open port needs to be internet-accessible. Many can be restricted to specific IP addresses (e.g., only your office network) without any functional impact. Port 22 open to the internet is one of the most common initial access vectors in breaches, if it does not need to be internet-facing, close it.

SSL/TLS Issues

SSL and TLS are the protocols that encrypt web traffic (the padlock in your browser). Findings in this category typically mean one of: the certificate has expired, the certificate is self-signed (not trusted by browsers), the server is using an outdated and insecure version of TLS, or the encryption configuration is weak.

What to do: Expired certificates should be renewed immediately, they cause browser warnings that damage customer trust. Outdated TLS versions should be updated by your hosting provider. Certificate issues are usually the easiest category of finding to resolve.

Software Version / Patch Issues

These findings say that a piece of software your servers are running is out of date and has known vulnerabilities. The finding will typically include the specific CVE numbers for the vulnerabilities in that version.

What to do: The fix is updating the software. Check with your DevOps or IT team whether updating is straightforward or whether there are compatibility considerations. For Critical CVSS findings, the urgency to update should override most compatibility concerns.

Missing Security Headers

Web servers can be configured to send security headers, instructions to browsers that help prevent certain types of attacks (like cross-site scripting or clickjacking). Missing security header findings mean your web server is not sending these instructions.

What to do: These are typically Medium severity and can be addressed by adding configuration to your web server or CDN. Your web developer can usually implement these in less than an hour.

Information Disclosure

This category covers findings where your systems are revealing information they do not need to, server software versions, directory structures, error messages that contain internal details, or configuration files that are publicly accessible.

What to do: These are typically Low-to-Medium severity but worth addressing because they help attackers plan more targeted attacks. Remove or suppress the unnecessary information.

The False Positive Problem

Not every finding in a security scan is a real issue. False positives, findings that technically match a pattern the scanner looks for, but are not actually exploitable in your environment, are a regular part of scan results. Common false positive scenarios:

• A vulnerability detected in a software version you are running, but the specific feature it exploits is not enabled in your configuration
• An open port that appears accessible from outside but is actually protected by a network-level firewall that the scanner bypassed
• A software version flagged as vulnerable because the scanner does not know you applied the patch backported by your Linux distribution

When a finding seems inconsistent with what you know about your environment, it is worth having your IT team or a developer validate whether the issue is real before investing significant effort in remediation. However: err on the side of assuming findings are real until proven otherwise, especially for Critical and High severity items. The cost of a false positive is a wasted hour of investigation. The cost of dismissing a real Critical finding can be significantly higher.

The Three Questions to Ask About Every Critical Finding

When you encounter a Critical finding and need to decide how urgently to act, ask these three questions:

1. Is this system actually reachable from the internet?

A Critical vulnerability in a system that is not internet-accessible is still serious, but less immediately urgent than one that is publicly reachable. If the vulnerable system can only be reached from inside your office network, the attack window is much smaller.

2. Is there a known exploit actively being used in the wild?

Some vulnerabilities have theoretical severity ratings that do not reflect their real-world exploitation rate. Others, particularly those tagged by CISA's Known Exploited Vulnerabilities (KEV) catalogue, are being actively exploited by real attackers right now. A CVE on the KEV list is a significantly higher priority than one that has been theoretically possible to exploit for five years but never seen in active campaigns.

3. What does this system have access to?

A vulnerability in a web server that only serves static marketing pages is less dangerous than the same vulnerability in a server that connects to your customer database or payment systems. The impact of successful exploitation depends on what the attacker can reach once they are inside.

What Your Monthly Report Should Tell You That a Raw Scan Cannot

Raw scan output gives you a list of findings. What it does not give you is:

• A trend, are you improving or getting worse month over month?
• Context, which findings are most likely to be exploited given current threat actor activity?
• Prioritisation, a ranked list of what to fix first, tailored to your environment
• A board-ready summary, something you can share with leadership without translating every line

This is the gap between a raw scan and a monthly security report. The report takes the data from continuous monitoring and turns it into a structured, actionable, shareable document that serves both technical remediation and management oversight. If you find yourself spending hours interpreting raw scan output every month, the monthly report is what you actually need.

Frequently Asked Questions

What is a CVSS score and why does it matter?

CVSS (Common Vulnerability Scoring System) is a standardised severity rating from 0 to 10 assigned to known software vulnerabilities. Scores of 9.0 to 10.0 are Critical, meaning exploitation is straightforward and the impact is severe. CVSS matters because it gives you a consistent way to compare the severity of different findings, but it should always be interpreted alongside context: a high CVSS score on a system that handles no sensitive data is less urgent than a moderate score on your customer-facing database server.

How should non-security staff interpret scan results?

Focus on three things: severity distribution (how many Critical and High findings exist), asset context (which systems are affected and what data they handle), and trend direction (are findings increasing or decreasing month over month). You do not need to understand every CVE number or port configuration. If a finding is Critical and affects an internet-facing system, escalate it to whoever manages that system. For everything else, use the severity labels to schedule remediation within the timeframes your security policy defines.

What are the most common findings in security scans?

The most frequent findings across external security scans are expired or misconfigured SSL certificates, outdated software versions with known CVEs, open ports that should not be internet-accessible (particularly SSH on port 22 and RDP on port 3389), missing security headers on web servers, and information disclosure through verbose error messages or exposed server version strings. Most of these are straightforward to fix once identified, and resolving them significantly reduces your organisation's attractiveness as a target for automated scanning tools that attackers use at scale.