Image Scanning
Find vulnerabilities.
Image Scanning is a free Cyber Security Academy lesson on CoddyKit — lesson 2 of 4. You can read the complete lesson below for free — then practise it hands-on in the browser with a built-in code editor and a 24/7 AI tutor. It is part of the Cyber Security Academy learning path, one of 4 lessons in the course, and your progress syncs across the web and the CoddyKit app.
What Is Image Scanning
Image scanning inspects a container image for known vulnerabilities, misconfigurations, and secrets before it runs.
It is like a security checkup for everything packed inside the image.
Why Scan Images
An image bundles an operating system, libraries, and your app.
Any one of those layers may carry a known vulnerability. Scanning finds them before attackers do.
CVEs and Databases
Scanners compare your image against public vulnerability databases.
Each known flaw has a CVE identifier, such as CVE-2023-1234, with a severity rating from low to critical.
Scanning the Layers
Images are built in layers. A scanner reads each layer and lists every installed package and its version.
It then checks which versions have published vulnerabilities.
Popular Scanners
Many free and commercial scanners exist.
- Trivy
- Grype
- Clair
They all share the same goal: list vulnerabilities found in an image.
A Simple Scan
Running a scan is usually one command. For example, with Trivy:
trivy image nginx:1.21The output lists each package, the CVE, and the severity.
Reading the Results
Focus on severity first. Critical and high findings need quick attention.
Each entry usually shows the installed version and the fixed version, telling you exactly what to upgrade to.
Finding Secrets
Modern scanners do more than CVEs. They also detect secrets accidentally baked into an image, such as API keys or private keys.
This helps catch leaked credentials early.
Scanning in CI/CD
The best time to scan is automatically, in your pipeline.
You can fail a build if critical issues appear:
trivy image --exit-code 1 --severity CRITICAL myapp:latestReducing the Surface
Smaller images have fewer things to scan and fewer vulnerabilities.
Using a minimal base image, such as a slim or distroless variant, shrinks the attack surface dramatically.
Scanning Is Ongoing
An image that was clean last month may not be clean today, because new vulnerabilities are discovered constantly.
Re-scan images regularly, not just once at build time.
Quick Check
What does a container image scanner primarily compare your image against?
Recap
Image scanning finds known vulnerabilities and leaked secrets in container images.
Run scans in CI/CD, prioritize critical findings, use minimal base images, and re-scan regularly to stay protected.
Frequently asked questions
Is the “Image Scanning” lesson free?
Yes — the full text of “Image Scanning” is free to read here on the web, and the Cyber Security Academy course includes 4 lessons in total. To practise it interactively (a built-in code editor and a 24/7 AI tutor) and unlock the rest of the Cyber Security Academy course, upgrade to CoddyKit PRO.
What will I learn in “Image Scanning”?
Find vulnerabilities. You practise Cyber Security Academy with hands-on code you run directly in the browser, and a 24/7 AI tutor answers your questions as you work through the lesson.
Do I need any experience to start Cyber Security Academy?
No prior experience is required. Cyber Security Academy on CoddyKit is structured for beginners through advanced learners; this is — lesson 2 of 4, so you can start here or from the beginning and move at your own pace.
How long does the “Image Scanning” lesson take?
Most CoddyKit lessons take about 5–10 minutes. Each one is bite-sized and interactive, so you make steady progress and pick up exactly where you left off across the web and the app.
Can I write and run code in this Cyber Security Academy lesson?
Yes. Every Cyber Security Academy lesson includes a built-in code editor, so you write and run real code right in your browser and get instant AI feedback — no local setup required.