To keep Composer-based projects secure, start by proactively using built-in tools and best practices because Composer does not check for malicious code by default. 1. Keep dependencies updated regularly by using composer outdated and automation tools like Dependabot or Renovate, but review changelogs before upgrading. 2. Audit packages before installation by checking download counts, repository activity, author credibility, and signs of compromise via Packagist or GitHub. 3. Use security tools such as the Security Advisories Checker, PHPStan, Psalm, and Snyk to detect vulnerabilities. 4. Limit plugin execution with the allowed-plugins setting in Composer 2.2 to control which plugins can run during installation. Together, these steps create multiple layers of protection that significantly reduce the risk of installing harmful packages.

You keep your Composer-based projects secure by staying proactive and leveraging built-in tools and best practices. Composer itself doesn't check for malicious code by default, but there are several steps you can take to reduce the risk of installing harmful packages.

Keep Your Dependencies Updated Regularly

Outdated packages are one of the most common sources of vulnerabilities — sometimes they contain known security flaws or may even get taken over by bad actors.

• Use composer outdated to see what needs updating.
• Consider using tools like Dependabot or Renovate to automate updates.
• Don’t just update blindly — review changelogs and breaking changes before upgrading.

Updating regularly helps close security gaps before they become real issues.

Audit Packages Before Installation

Before adding a new package, it’s worth spending a few minutes checking its legitimacy and maintenance status.

Here’s what to look at:

• How many downloads does it have? Popular packages tend to be safer (but not always).
• Is the repository actively maintained? Check commit history and open issues.
• Who is the author? Stick to well-known vendors or verified publishers when possible.
• Look for signs of compromise: sudden ownership changes, suspicious commits, or unexpected version bumps.

You can also use platforms like Packagist and GitHub to inspect package details and source code.

Use Security Tools Designed for PHP and Composer

Composer integrates with tools that help detect malicious or vulnerable packages.

Some useful ones include:

• Security Advisories Checker – Checks if any installed packages have known vulnerabilities.
• PHPStan or Psalm – Static analysis tools that might catch weird patterns in code.
• Snyk or [GitHub Dependabot alerts] – These scan your dependencies and warn about security issues automatically.

These tools don’t stop everything, but they do catch a lot of red flags early.

Limit What Composer Can Do With allowed-plugins

Composer 2.2 introduced the allowed-plugins setting, which lets you control which plugins are allowed to run during installation.

For example, you can restrict execution like this in your composer.json:

{
  "config": {
    "allow-plugins": {
      "composer-plugin-name": true,
      "another-safe-plugin": true
    }
  }
}

This prevents unknown or potentially dangerous plugins from running arbitrary code when someone installs dependencies.

Most of these steps aren’t hard to implement, but together they create layers of protection. You won’t block every threat, but you’ll make it much harder for malicious packages to slip through.

The above is the detailed content of How do I prevent malicious packages from being installed through Composer?. For more information, please follow other related articles on the PHP Chinese website!