Hours of development labor can be saved by adding a NuGet package. You can leverage an existing library for database access, logging, validation, or API connectivity rather than creating everything yourself. However, there may be issues if a package is installed without first being checked. It could cease getting updates, provide features your program doesn't need, create incompatible dependencies, or have known vulnerabilities.
A package that builds successfully is not automatically safe or suitable for production. Before adding a dependency, you should understand who maintains it, what it depends on, how it is licensed, and whether it is appropriate for your project. In this article, we will look at practical ways to inspect a NuGet package, check its dependencies and security advisories, and decide whether it is ready to use in a .NET application.
Why You Should Review a NuGet Package First?
A NuGet package becomes part of your application's dependency chain. Even if you use only one method from a library, its dependencies may introduce additional code into your application.
For example, a package used for HTTP communication might depend on another library for serialization or authentication. If one of those dependencies has a vulnerability or becomes incompatible with your target framework, your application may be affected.
Before installing a package, consider these questions:
- Does it solve a real problem in the application?
- Is the package maintained and compatible with the target framework?
- Does it have known security vulnerabilities?
- Are its dependencies necessary and trustworthy?
- Does its license permit your intended use?
- Can the team maintain the package over time?
These checks do not need to take hours. A few simple commands and a review of the package metadata can catch many common problems.
Step 1: Check the Package Details
Start by reviewing the package information in the NuGet package manager or the package's metadata. Pay attention to the package ID, publisher information, supported frameworks, release history, license, and project documentation.
Do not select a package based only on its name. Two packages may have similar names but different maintainers, capabilities, and dependency requirements.
For example, if you need structured logging, compare packages based on their actual features and compatibility with your application rather than choosing the first result in a search.
Check whether the package has a clear purpose and whether its documentation explains how to configure it correctly.
Review the Package's Release History
A package with recent releases may be easier to maintain, but release frequency alone does not prove that it is safe.
Look for signs that the maintainers address bug reports, publish fixes, and document breaking changes. An older package may still be appropriate if it is stable and actively supported for your use case.
Be cautious when a package has unclear ownership, unexplained changes, or documentation that does not match its published behavior.
Step 2: Inspect the Package Using the .NET CLI
You can search for packages and inspect their metadata without immediately adding them to your project.
To search NuGet for a package, run:
dotnet package search Serilog
This searches for packages matching the supplied term. Review the results and identify the package that matches your requirements.
To inspect a package already installed in your project, run:
dotnet list package
This displays the project's package references.
For more detail about a particular dependency, you can use:
dotnet list package --include-transitive
This includes transitive dependencies: packages brought into your project by other packages.
The exact output depends on your .NET SDK version and project type. If a command is unavailable in your environment, check the syntax supported by the installed SDK.
Step 3: Check Package Compatibility
Before adding a package, confirm that it supports your project's target framework.
For example, a project might contain the following configuration:
<Project Sdk="Microsoft.NET.Sdk">
<PropertyGroup>
<TargetFramework>net8.0</TargetFramework>
<Nullable>enable</Nullable>
<ImplicitUsings>enable</ImplicitUsings>
</PropertyGroup>
</Project>
The project targets .NET 8 in this example. A NuGet package may support several target frameworks, such as .NET Standard and specific versions of .NET. However, package compatibility depends on the frameworks declared by the package and the compatibility rules used by NuGet.
Before installation, check the package's supported frameworks and any documented runtime requirements.
After adding a package, restore and build the project:
dotnet restore
dotnet build
A successful build confirms that the project can compile with the resolved dependencies. It does not prove that the package is secure or that its runtime behavior is correct.
For packages that perform important operations, such as database access or authentication, add tests that verify the expected behavior.
Step 4: Check for Known Vulnerabilities
Security should be part of package selection, not something you check only after deployment.
The .NET CLI can report known vulnerabilities affecting packages in your project.
Run:
dotnet list package --vulnerable
To include transitive dependencies in the report, use:
dotnet list package --vulnerable --include-transitive
These commands help identify package versions associated with known security advisories in the available advisory data.
If the output reports a vulnerability, review the affected package version, severity, available fixes, and the conditions required for exploitation.
For example, a vulnerability may affect only a specific feature or configuration. That information helps you assess the risk, but it does not mean you should ignore the finding when the feature is not obviously used.
If a fixed version is available, determine whether upgrading is compatible with your application and test the change before deployment.
You should also remember that an empty vulnerability report does not guarantee that a package is safe. Newly discovered issues, incomplete advisory data, or vulnerabilities that have not been publicly reported may not appear.
Step 5: Review Direct and Transitive Dependencies
A direct dependency is a package your project references explicitly. A transitive dependency is brought in by another package.
Suppose your application references a logging library, and that library depends on another package for configuration. Your application now has an additional dependency even though you did not install it directly.
Use this command to inspect the dependency list:
dotnet list package --include-transitive
Review packages that introduce many dependencies, especially when those dependencies are unrelated to the functionality you need.
A larger dependency tree is not automatically bad, but every additional dependency adds another component that may require updates, compatibility checks, and security review.
If a vulnerability appears in a transitive dependency, check whether an updated version of the parent package resolves it. Avoid forcing a different dependency version without checking compatibility, because the parent package may rely on particular behavior.
Step 6: Check the Package License
Package licensing determines how you may use, modify, and distribute the software. This matters when developing commercial applications, distributing software to customers, or incorporating packages into products with specific licensing requirements.
Check the license information provided by the package maintainers. Confirm that the license file or declared license matches the actual package and that your intended use complies with its terms.
Do not assume that a publicly available package can be used without restrictions.
For business-critical applications, record the licenses of direct and transitive dependencies and follow your organization's software approval process. If the licensing terms are unclear, request a review from the appropriate legal or compliance team.
Step 7: Install the Package Using an Explicit Version
Once you have reviewed the package, install it with a deliberate version selection.
For example:
dotnet add package Serilog --version 4.0.0
This command illustrates installing a specific package version. The version shown is an example, not a recommendation to use that version in a new application.
Select a version that is compatible with your project and meets your maintenance and security requirements.
After installation, inspect the project file. A package reference may look like this:
<ItemGroup>
<PackageReference Include="Serilog" Version="4.0.0" />
</ItemGroup>
Keep the version consistent with the one you reviewed and tested.
For projects that use central package management, package versions may instead be declared in a Directory.Packages.props file. Check the configuration used by your repository before changing individual project files.
Commit the appropriate project configuration and lockfiles used by your build process so that other developers and CI/CD agents can restore consistent dependencies.
Step 8: Test the Package Before Production
Installing a package is only the beginning. Verify that it works correctly in the application.
Follow these steps:
- Restore the project and confirm that dependency resolution succeeds.
- Build the solution and review warnings or errors.
- Write tests for the functionality that uses the package.
- Test failure cases, invalid inputs, and unexpected responses where relevant.
- Review runtime behavior and application logs.
- Run the project's security and dependency checks.
- Verify the result in a staging environment before deploying it.
If the package performs network operations, test timeouts and connection failures. If it handles sensitive information, verify that it does not expose secrets through logs or error messages.
For packages that affect performance, measure their impact under representative workloads instead of assuming they will improve performance.
Common Mistakes to Avoid
One mistake is selecting a package only because it has a high download count. Popularity can indicate adoption, but it does not establish security, maintenance quality, or compatibility.
Another mistake is installing the latest version without checking breaking changes. A newer release may require changes to your code or target framework.
Do not rely only on direct dependency checks. Vulnerabilities can exist in transitive packages that your project receives indirectly.
Also avoid suppressing security warnings without recording why the finding is not applicable or how the risk is being managed.
Finally, do not assume that a package is trustworthy simply because it is available through NuGet. Review the publisher, package identity, version history, license, and dependency tree.
Best Practices for Managing NuGet Dependencies
For a maintainable .NET project, follow these practices:
- Prefer packages that have clear documentation and a defined purpose.
- Review compatibility before installation.
- Run vulnerability checks regularly, including transitive dependencies.
- Keep package versions explicit and manage updates through source control.
- Review licenses before using packages in commercial products.
- Test package upgrades before releasing them.
- Remove dependencies that are no longer needed.
- Use automated dependency and security checks in CI/CD pipelines.
- Investigate warnings instead of treating a successful build as proof of safety.
For larger teams, maintain a record of approved dependencies and establish a process for handling vulnerable or abandoned packages.
Advantages and Limitations of Package Review
Reviewing a package before installation can reduce avoidable security risks, prevent compatibility problems, and make dependency updates easier to manage.
It also helps teams understand which external libraries their applications rely on and why those libraries are necessary.
However, package metadata and automated security reports cannot prove that every line of code is safe. A package may contain an undiscovered vulnerability, and a well-maintained package can still be unsuitable for a particular application.
Use package review as one part of a broader development process that includes secure coding, testing, monitoring, and regular maintenance.
Summary
Before adding a NuGet package, check its purpose, publisher, compatibility, license, release history, and dependencies. Use the .NET CLI to inspect installed packages and identify known vulnerabilities, including issues in transitive dependencies.
Choose a version that fits your project, test it before production, and keep dependency configuration under source control. A few minutes spent reviewing a package can prevent unnecessary dependencies, difficult upgrades, and avoidable security problems later.
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