How to detect and fix common container security vulnerabilities

Key takeaways

Anyone who deals with container security knows that it’s far from just a DevOps concern – it’s critical to infrastructure protection, and it involves hours upon hours of cross-functional effort. Here’s what you need to know:

• Many container security vulnerabilities can be avoided altogether with the right tools and practices.
• Common risks when it comes to container security include outdated base images, leaked private data, misconfigurations, and embedded malware.
• Today’s scanners are great at identifying these issues at build, deploy, and runtime stages, but visibility isn’t resolution.
• Fixing vulnerabilities often starts with selecting secure base images and automating patching strategies.
• Continuous scanning is crucial to agile development, but alone it’s not enough.

What are container security vulnerabilities?

Container security vulnerabilities (CVEs) are weaknesses within containerized environments that can be exploited by attackers to gain unauthorized access, disrupt services, or exfiltrate confidential data. These vulnerabilities can exist in container images, orchestrator configurations like Kubernetes, and the container runtime itself.

And unlike traditional systems, containers are typically built from layered images, which essentially means that a single vulnerable base image can propagate issues across hundreds of workloads. So if a hacker manages to exploit a CVE in your base image, so much is suddenly at risk. The rapid adoption of containers, which are lightweight, portable environments for packaging and running applications, has made them a primary target for attackers. 

So, what triggers these vulnerabilities? They can stem from a whole host of things – from outdated libraries to misconfigurations to hardcoded credentials, or even unvetted dependencies pulled from public registries. According to numerous security reports, the majority of container breaches are caused by misconfigurations and overlooked vulnerabilities in the supply chain. Without a robust strategy to detect and mitigate these issues, organizations risk exposing highly sensitive services and data.

All this said, to navigate container vulnerabilities, you need to first understand how they differ from traditional security threats. Containers are extremely dynamic, which demands a security posture that’s equally agile. To stop them head-on, you need to incorporate static analysis and real-time monitoring.

Most common container security risks to watch for

As mentioned above, container environments are dynamic by design, but that very flexibility is responsible for introducing serious risks. Below are some of the most common container security vulnerabilities you need to watch for:

• Outdated base images: Most containers aren’t built from scratch. They typically use open-source base images, which come from a public registry. As a result, they’re often filled with hundreds, if not thousands, of critical CVEs (Common Vulnerabilities and Exposures).
• Hardcoded secrets and credentials: Secrets like API tokens or SSH keys can often mistakenly get baked into images or checked into version control. And once leaked, these can give attackers dangerous, unrestricted access.
• Misconfigured container permissions: If you run containers as root or with excessive privileges, you also increase the blast radius of any exploit or attack.
• Insecure or deprecated packages: Using unverified or old dependencies can bring exploitable CVEs into the container from external ecosystems.
• Embedded malware or backdoors: Containers from untrusted registries can contain intentional and unintentional malicious code, which brings with it tremendous risk.
• Open network ports: If you unnecessarily expose ports or misconfigure network policies, you’re leaving containers accessible from the public internet.
• Unchecked third-party software: Pulling community-built images without scanning them first is a sure way to inherit tons of unknown vulnerabilities. 
• Excessive image bloat: Larger images often contain unnecessary components, tools, and files, which not only increases the attack surface but also makes vulnerability management significantly more challenging.
• Improper file and directory permissions: If you don’t lock down file permissions inside containers, attackers can exploit writable paths to insert or execute malicious code.

Each of these security risks gives a taste of the potential impact of a breach. The good news? The majority can be mitigated with the right approach and tools.

Want to uncover and eliminate your container blindspots? Start here: CVE blindspots in container infrastructure

How to detect vulnerabilities using a container scanning tool

Container scanners like Trivy, Grype, and Snyk are designed to uncover vulnerabilities within images by analyzing their contents, configurations, and software components.

How they work

Scanners inspect every layer of the container images, comparing installed packages and configurations against known vulnerability databases like:

• NVD (National Vulnerability Database)
• GitHub Security Advisories
• Vendor-specific CVE feeds (e.g., Alpine, Debian, Red Hat)

They also flag misconfigurations, exposed secrets, and insecure permissions.

These tools use both static and dynamic analysis techniques: Static scanning analyzes the image contents without executing the code, identifying the vulnerable packages and dependencies. Dynamic scanning, on the other hand, may observe containers at runtime to identify behavior that indicates compromised elements or misconfigurations.

What they scan for

• Known vulnerabilities in OS and app libraries
• Deprecated or vulnerable packages
• Insecure environment variables or secrets
• Misconfigurations in Dockerfiles and image metadata
• Over-permissive capabilities and file permissions
• Embedded tools or binaries that should not be in production environments

When to use scanners

Container scanning should be done at every stage in the development lifecycle:

• Build time – At this stage, scanners are key to catching issues before code hits production. Lots of tools integrate with CI/CD pipelines to automate scanning on every commit.
• Deploy time – Scanning images right before they’re shipped is essential to providing an additional gate.
• Runtime – Scanning at runtime is extremely important for monitoring running containers for newly discovered vulnerabilities or behavior anomalies. Once it’s live, you need to be even more intentional.

Best practices to fix vulnerabilities in containers

Detecting CVEs is only the first step. Here’s how to prevent them and reduce your attack surface to minimize risk:

1. Start with secure base images

Use minimal, hardened base images that only contain the packages you need. Consider sources like:

• Distroless (for an image stripped of package managers and shells)
• Alpine (for a minimal Linux footprint)
• Echo (for fully functional CVE-free base images that are built and kept CVE-free over time)

Learn more: Building slim containers

2. Implement automated image rebuilds

Base images can become outdated quickly, which is why automating updates and patching is a great way to ensure dependencies are always current. This avoids the “vulnerability drift” that often occurs over time. Image rebuild automation should be tied to CVE feeds so that any time a new vulnerability is published, a fresh build gets triggered, and notifications get sent when relevant images are in use.

3. Remove unnecessary packages

Try to avoid installing curl or bash unless you truly need them, because every additional tool increases the surface area for potential exploits. Slimmer images can also improve performance and reduce deployment times, which enables faster iterations and less attackable code.

4. Avoid hardcoded secrets

Use secret management tools like Vault, AWS Secrets Manager, or Kubernetes Secrets, rather than storing tokens or credentials inside your images. Even in internal test environments, it's important to simulate production secret handling to avoid bad habits entering your CI/CD pipelines.

5. Enforce least privilege

Run containers as non-root users, using capabilities and seccomp/apparmor profiles to limit what each container can do. For Kubernetes, try to apply PodSecurityStandards and role-based access control (RBAC) to prevent privilege escalation or lateral movement.

6. Use multi-stage builds

Implement multi-stage Docker builds to help keep final images lean and free of dev or test tooling that doesn’t belong in production. You can also try splitting build environments from runtime containers to ensure that unnecessary tools like compilers or linters don’t wind up in your final containers.

Why continuous scanning is essential in DevSecOps pipelines

When it comes to image scanning, it’s not enough to do it once. New vulnerabilities are always popping up so in order to ensure your images stay secure in the long-run, it’s essential to make sure continuous scanning is embedded in your DevSecOps workflow.

1. Vulnerabilities are discovered daily

It’s very possible that an image you scan today will show up clean, and tomorrow, it wouldn’t. This is particularly common in long-standing software that’s rarely updated after deployment. That’s why, to avoid the risk of unknowingly deploying your apps with known vulnerabilities, you must continuously scan your container images on a regular basis. 

2. Agile cycles need agile security

In order to ensure you’re continuously scanning and scaling, the process can’t be manual. Weekly or daily deployments demand automated scanning integrated into your CI/CD pipeline. Otherwise, it’s just not sustainable.

3. Runtime environments differ

Some vulnerabilities only emerge under runtime conditions, which is why continuous monitoring is a great way to identify real-world threats that static scans miss. Runtime scanning tools also enable correlated alerts with active container instances, so that your teams can effectively understand what is truly exploitable and actionable.

3. Shift-left–shift-right synergy

A strong security posture involves both shifting left (build time) and right (runtime) in order to promote fast detection and accurate, real-time remediation. 

For more on the challenge of managing vulnerabilities at scale, read: The vulnerability management dilemma

FAQs

What causes container security vulnerabilities?

Container security vulnerabilities typically stem from one or more of the following sources:

• Vulnerable base images: Most applications are built upon open source base images, which developers pull from a public registry. Since they’re open to everyone, they’re often filled with lots of CVEs that cascade throughout the rest of your application.
• Third-party dependencies: Your application code will often include some open source libraries or frameworks as well. If those dependencies have unresolved vulnerabilities, they’ll also become part of your container’s attack surface.
• Misconfigurations: If your containers are deployed with overly permissive settings (e.g. running as root, excessive capabilities, or insecure network exposure), you’ll inherently be at greater risk.
• Unpatched runtime environments: If your containers rely on outdated or insecure host kernels or container runtimes (like Docker or containerd), attackers can exploit vulnerabilities at the infrastructure level.
• Supply chain attacks: Malicious or compromised components can also be introduced during the CI/CD process, build pipeline, or even through tampered dependencies.

Can container vulnerabilities be fixed automatically?

Yes. To a large extent, container vulnerabilities can now be fixed automatically, particularly when it comes to base image vulnerabilities. Modern tools like echo automate vulnerability the remediation process by:

• Building CVE-free base images from scratch that mirror the functionality of the original image.
• Ensuring outdated packages are not included, rather than simply patching them in place, to prevent the accumulation of unused vulnerable code, which increases attack surfaces.
• Using AI to automatically patch and harden images if new vulnerabilities arise.

This approach means teams no longer have to chase individual CVEs in their base images or rely on alerts from scanning tools. Instead, they can use secure-by-design infrastructure that’s constantly updated to eliminate vulnerabilities at the source.

Even with solutions like echo, application-level issues will often still require developer review, so container vulnerabilities as a whole can not automatically be fixed right now. 

Are container scans enough to secure my cloud-native apps?

No, container scans are an important starting point, but scanning alone is certainly not enough. While container image scanning tools like Trivy, Grype, or Snyk help identify known vulnerabilities, they don’t:

• Prevent CVEs from entering your environment – they just give you visibility into what’s already there.
• Fix issues automatically – they still require active intervention or separate patching steps to eliminate the CVEs they uncover.
• Catch misconfigurations or insecure defaults, especially at runtime.
• Eliminate zero-days or logic flaws, which scanners likely won’t detect.

That’s why a strong cloud-native security strategy includes:

• Using CVE-free base images.
• Continuous scanning and monitoring of runtime behavior and access controls.
• Ongoing hardening of container configurations and limiting privileges.

What’s the difference between image scanning and runtime scanning?

The key difference is when and what they scan:

Image scanning happens before deployment to catch issues early, during development or CI/CD. This process involves inspecting container images for:

• Outdated software versions
• Known CVEs in OS packages and libraries
• Dependency vulnerabilities
• Insecure or excessive permissions

Runtime scanning, on the other hand, happens after deployment. It protects against active exploitation, especially for zero-days or misconfigurations missed earlier, monitoring containers in production for:

• Unexpected processes or behaviors
• Lateral movement attempts
• File system tampering
• Privilege escalation or network abnormalities
  

Ideally, you should use both types of scanning to reduce risk before deployment and detect issues that emerge in production.