Container security: Frameworks, risks, and fundamentals

Containers changed everything about deploying software. Suddenly, you could package an app with all its dependencies, ship it anywhere, and have it run exactly the same way. No more "works on my machine" complaints. Development teams went from deploying once a week to shipping multiple times a day. But here's the problem: teams optimized for speed and forgot that speed without security is just a faster way to get hacked.

If you're running containers in production (or planning to), you've probably felt that nagging concern about vulnerabilities, compliance requirements, or whether your current security approach actually covers all the bases. (If not, you should.) Maybe you're relying on scanning tools or ad hoc processes, and you're wondering if there's a more complete strategy.

This guide will walk you through what container security actually means, why it matters more than you might think, and the practical steps you can take to secure your containerized applications from build time through runtime. We'll cover the fundamentals, common vulnerabilities, best practices, and tools that can help.

What is container security?

Container security is the practice of protecting containerized applications and their infrastructure throughout the entire container lifecycle. Unlike VMs, which include a full operating system, containers share the host operating system kernel and rely on Linux namespaces and control groups for isolation. This makes them lighter and faster to spin up, but it also means a compromised container can escalate privileges to the host or access data from other containers if the right security controls aren't in place.

Container security applies across four stages:

• Build time: This is where you choose base images, add dependencies, and package your application code. Security decisions made here determine what vulnerabilities and risks make it into your container images before they ever reach production.

• Storage: Container images sit in container registries (like Docker Hub, Amazon ECR, or Google Artifact Registry) before deployment. These repositories require proper access controls, vulnerability scanning, and image signing to prevent tampering to be secure.

• Deployment: When you deploy containers to orchestration platforms like Kubernetes, you're configuring network policies, permissions, resource limits, and runtime security policies. Misconfigurations at this stage can expose your workloads to unauthorized access or privilege escalation.

• Runtime: Once containers are running, runtime security tools monitor for anomalous behavior, policy violations, and potential security incidents. Runtime security tools watch for threats like malicious code execution or unexpected network connections.

Securing containers starts before runtime. The best container security strategies focus on prevention during build and throughout the software supply chain, rather than only detecting problems after they’ve already been deployed.

Why container security matters (more than you think)

Containers power production workloads that handle customer data, financial transactions, and business operations. When containers are insecure, the consequences are more serious than just technical problems. You're looking at potential data breaches, compliance failures, service outages, and damage to customer trust.

Here's what you get with strong container security:

• Reduced attack surface and vulnerability exposure: Minimal, hardened container images with fewer components mean fewer places for attackers to find weaknesses. When you start with secure base images, you're not inheriting hundreds of Common Vulnerabilities and Exposures (CVEs) before you've even added your own code.

• Compliance with regulatory frameworks: Meeting standards like FedRAMP, PCI, and NIST is a must for many organizations. Container security tools that provide built-in compliance readiness, software bill of materials (SBOMs), and provenance data make audits significantly less painful.

• Protecting sensitive data and maintaining customer trust: Containers often process customer information, financial records, and proprietary data. Proper security controls, from secrets management to network policies, prevent unauthorized access and exposure that could harm your reputation and bottom line.

• Improved deployment reliability and stability: Security and stability go hand in hand. Containers with fewer vulnerabilities and proper configuration are less likely to fail in production or introduce unexpected behavior that breaks your services.

• Faster remediation through proactive vulnerability management: Finding and fixing vulnerabilities at build time is faster and cheaper than patching production systems. Automated scanning and continuous rebuilds mean you're not scrambling to respond to every new CVE.

• Better developer productivity with secure defaults: When security is baked into your base images and workflows, developers don't need to become security experts. They can focus on building features while the platform handles the security fundamentals.

Common critical vulnerabilities lurking in containers

Container security threats appear at multiple points in the container lifecycle, often from insecure builds, misconfigurations during deployment, or compromised upstream components in your software supply chain. Because containers are fast-moving and ephemeral, these risks can multiply quickly if they're not addressed early.

Unverified and outdated base images

Your base image is the foundation of your container. If that foundation is shaky, everything built on top of it is more likely to wobble. Many teams pull base images from public repositories like Docker Hub without verifying their source or checking how recently they've been updated. An outdated base image might contain dozens or hundreds of known vulnerabilities right from the start.

Unverified images introduce another risk: you don't know what's actually inside them. A bad actor could publish a popular-looking image that includes a backdoor or cryptocurrency miner. Using minimal, verified images with cryptographic signing dramatically reduces this risk.

Unpatched dependencies and misconfigurations

Even if your base image is clean, your application depends on third-party libraries, frameworks, and system packages that have their own vulnerabilities. The challenge is keeping up with patches at scale across hundreds of microservices, each with its own dependencies. By the time you've patched one service, five more CVEs have been published. You’re playing non-stop catch-up.

Misconfigurations make these problems worse. Running containers as root, overly permissive network settings, exposing unnecessary ports, and failing to set resource limits all create additional attack surface. These issues often slip through because teams lack centralized visibility or automated policy enforcement across their container environments.

Insecure secrets management

Surprisingly, teams ofter hardcode credentials or API keys directly into container images, which is one of the fastest ways to leak sensitive data. When secrets are baked into images or stored in plaintext configuration files, they can be exposed when images get pushed to public registries, developers accidentally commit credentials to repositories, or attackers get read access to your container registries.

Questionable container image provenance and integrity

How do you know your container image is actually what you think it is? How do you know it hasn't been tampered with between your build pipeline and your production environment? Compromised upstream dependencies are a real threat in the software supply chain. Signed images and SBOMs help mitigate this risk.

Get started with container security best practices

Container security best practices provide the bridge between understanding risks and implementing solutions. Core categories include:

• Secure builds: Choosing verified, minimal base images and patching dependencies early

• Proactive vulnerability management: Continuous scanning and automated remediation when new CVEs are discovered

• Access control and least privilege: Limiting container permissions and implementing RBAC in Kubernetes

• Supply chain integrity: Signing images, generating SBOMs, and maintaining provenance data

For a complete breakdown of the best practices for container security, check out our container security best practices guide.

Container security tools and technologies

Container security requires multiple layers of tooling to cover the entire lifecycle. No single product can address every risk from build time through runtime. The goal is to create a toolchain that has your back throughout build, registry, runtime, and compliance.

Image scanning tools

Image scanners analyze container images to detect known vulnerabilities in base images, operating system packages, and application dependencies. They compare the contents of your image against databases of known CVEs and help prioritize remediation work. However, keep in mind that scanning is inherently reactive: By the time a scanner detects a vulnerability, that vulnerability has already been introduced into your image.

Signing and provenance solutions

Image signing and provenance tools provide cryptographic verification that a container image came from a trusted source and hasn't been tampered with. Tools like Sigstore and Cosign create signed attestations that include the source repository, commit hash, build system, and build time. The standalone signing solutions require manual implementation, including key management, build pipeline integration, and deployment-time verification, so you’ll need to pair them with other tools to make them effective.

Runtime protection platforms

Runtime security tools monitor containers while they're running in production, watching for anomalous behavior, policy violations, or signs of compromise. They use behavioral analysis and machine learning to spot threats that got past your build-time and deployment-time controls. As with image scanners, you shouldn’t rely on runtime tools alone because they find problems already happening in your production environment. They work best when combined with prevention earlier in the lifecycle.

Why leading organizations trust Chainguard for container security

Chainguard delivers container security that minimizes risk and friction while maximizing developer productivity. The approach focuses on prevention rather than detection.

• Minimal, hardened, zero-CVE base images: Every Chainguard image includes only what your application needs, with zero known vulnerabilities when it ships. See how Anduril achieved zero CVEs.

• End-to-end supply chain security with SBOMs, signing, and provenance: Every image includes complete transparency about what's inside and how it was built. SBOMs, cryptographic signatures, and SLSA attestations are built in.

• Automated, continuous updates with CVE SLAs: Security researchers discover new vulnerabilities daily. Chainguard engineers respond by releasing patched images within hours through automated rebuilds.

• Compliance readiness: Chainguard images meet strict federal security requirements out of the box, including FIPS 140-2 validated cryptography and STIG hardening. Learn how Snowflake achieved FedRAMP High in half the time.

• Thousands of continuously maintained container images: Chainguard provides hardened alternatives for the most popular open-source software and programming language ecosystems, giving developers a choice without compromising security.

• Integration with existing CI/CD and Kubernetes workflows: Chainguard images work with your existing DevOps tools and processes without requiring infrastructure changes.

• Distroless architecture for minimal attack surface: By removing unnecessary packages, shells, and package managers, distroless images dramatically reduce potential vulnerabilities.

Ready to see how Chainguard can improve your container security posture? Talk to the team to learn how organizations are preventing vulnerabilities before they reach production.