Unmaintained software refers to components or libraries that are no longer actively developed or supported. Without updates, these components become vulnerable to unresolved bugs and security flaws. Users of such software face challenges in maintaining functionality and securing applications, often requiring them to develop their own patches, an effort that can be costly and time-intensive.

While reduced activity in a project might sometimes indicate maturity, it often signals abandonment. The absence of support increases the risks of unresolved vulnerabilities, compatibility issues, and potential system compromises.

In this lesson, you will explore the risks posed by unmaintained open-source software. You will step into the shoes of a developer who is facing challenges caused by a deprecated library in their application. The lesson includes real-world examples, strategies to assess project health, and measures to reduce reliance on unmaintained components.

Imagine a fintech startup, "QuickFinance," using an open-source library, NumCalc for financial computations. The library was a perfect fit until QuickFinance needed to implement a new feature to handle negative interest rates.

They detected this issue while testing the new feature. All of their results were inaccurate. Investigating further, they discovered a bug in the NumCalc library. They filed an issue on the repository, only to learn that NumCalc had been archived a year ago with no plans for further maintenance.

The team debated between replacing the library or creating an internal patch. However, the lack of domain expertise made patching risky. Moreover, migrating to a new library was expensive due to dependencies. They created a pros and cons table of staying vs. switching.

After researching alternatives, the team identified a maintained library, CalcPro. Though promising, the migration required extensive refactoring and retraining. In the end, they decided to migrate. It was successful but costly. The team instituted a new policy: all dependencies must be reviewed quarterly for activity and maintenance status to avoid similar pitfalls.

QuickFinance's experience underlined the importance of proactive monitoring for software dependencies. They emphasized choosing libraries with clear support commitments and fallback strategies in case of abandonment.

To understand the challenges of unmaintained software, let’s analyze QuickFinance’s case in detail. The issue arose from using an outdated and unsupported library, NumCalc, which no longer received updates or bug fixes. Here, we break down the key factors contributing to the risk and explore the code-level issues and their solutions.

Lack of maintenance signals

The lack of commit activity, unresolved issues, and absence of maintainers indicated that NumCalc was unmaintained. A quick check of the repository’s status would have revealed this before adoption.

Example indicators for maintenance status include the absence of commits or updates within the last year, signaling a lack of ongoing development activity. Additionally, repositories marked as archived or explicitly deprecated by the maintainers indicate that the project is no longer actively supported. A noticeable lack of responses to issues or pull requests further underscores the project's inactive status, reflecting minimal or no engagement from its maintainers with the developer community.

The Python snippet uses a fictional numcalc library to calculate compound interest. The calculate_interest function takes the principal, rate, and time as arguments and attempts the computation within a try-except block. When provided with a negative interest rate, the library raises an exception because it does not handle such inputs. The reliance on an unmaintained library like numcalc creates a vulnerability, as there are no fixes available for this issue, forcing developers to find a replacement or patch it themselves.

In the Go snippet, the numcalc library is imported and used to calculate compound interest. The Compound function takes parameters for principal, rate, and time, but when given a negative interest rate, it fails to compute the result and returns an error. The program logs this error, but the library's inability to handle this input remains unresolved because it is no longer maintained. This demonstrates a key vulnerability: reliance on unsupported software leaves the application exposed to limitations and bugs that cannot be fixed by the library’s maintainers.

The JavaScript snippet utilizes a hypothetical numcalc library to perform a compound interest calculation. The function call is wrapped in a try-catch block to handle errors. When the input includes a negative interest rate, the library fails and throws an error. Since numcalc is unmaintained, developers cannot expect any patches to resolve this issue. This leaves the application vulnerable to scenarios where valid edge cases, like negative rates, cannot be processed correctly.

The PHP code uses a fictional NumCalc library to calculate compound interest. It tries to handle unexpected inputs, such as a negative interest rate, by wrapping the computation in a try-catch block. However, since NumCalc is unmaintained, it does not support this edge case and throws an exception. This leaves the application unable to compute the value correctly. The vulnerability lies in the reliance on an unmaintained library, which cannot provide updates or fixes for such scenarios.

This C# program uses the hypothetical NumCalc library to compute compound interest. The code encapsulates the calculation in a try-catch block to catch and display any errors. However, the library's inability to handle a negative interest rate results in an exception. Since the library is no longer maintained, there’s no way to fix this issue, making the application unreliable. This demonstrates the risk of using unsupported libraries, as their inability to handle edge cases can compromise functionality.

In this Java example, the NumCalc library is used to perform a compound interest calculation. The program attempts to handle errors by catching exceptions, but when given a negative interest rate, the library fails. As NumCalc is unmaintained, developers cannot rely on future patches to address such bugs. The reliance on outdated software creates a vulnerability, as the application cannot handle certain valid inputs and must seek alternatives or workaround solutions.

Unmaintained software poses significant risks to an application's stability, security, and reliability. When using unsupported libraries, applications are exposed to unresolved vulnerabilities that attackers can exploit. Additionally, as dependencies grow outdated, compatibility with other components or newer systems diminishes, leading to potential functionality failures. The lack of updates also increases the effort required to maintain the application, as developers must take responsibility for patching issues or finding alternatives, consuming time and resources.

Mitigating the risks of unmaintained software requires a proactive approach that includes monitoring dependencies, managing them strategically, and preparing fallback plans. Before adopting a new library, it’s crucial to evaluate its health by checking its commit history, release frequency, and responsiveness to reported issues. Projects with clear documentation on long-term support (LTS) versions or defined support lifecycles are generally more reliable.

Once a dependency is in use, regular monitoring helps catch potential risks early. Tools like dependency scanners can track updates, flag deprecated libraries, and alert teams to archived repositories. A periodic review of all dependencies ensures outdated components don’t become a security or compatibility issue down the line.

Having a backup plan is equally important. Maintaining an inventory of critical dependencies, along with possible alternatives or mitigation strategies, helps teams respond quickly if a library is abandoned. This could involve identifying equivalent replacements or preparing for internal patching to keep an unsupported dependency functional.

In cases where a critical library becomes unmaintained, contributing to its upkeep or forking the repository can be a viable solution. While maintaining a project in-house requires resources, it ensures continuity and stability for essential components. To further minimize risk, reducing the overall dependency footprint is a smart strategy. Where possible, relying on built-in language libraries or well-supported frameworks can help limit exposure to unmaintained code.

In the mitigated Python code, the unmaintained numcalc library has been replaced with the maintained calcpro library. The calcpro library provides active support, regular updates, and fixes for edge cases, such as handling negative interest rates. This ensures that the application can rely on accurate calculations without fear of unresolved bugs or lack of support. Unlike the vulnerable code, this approach reduces risk by using a well-maintained dependency.

The mitigated Go code replaces the unmaintained numcalc library with calcpro, an actively maintained alternative. The new library is designed to handle edge cases, including negative interest rates, avoiding runtime errors. The secure code benefits from the ongoing development and timely patching of calcpro, making it a safer choice compared to the vulnerable example that relied on unsupported software.

The mitigated JavaScript code substitutes numcalc with calcpro, a maintained library that addresses the shortcomings of its predecessor. This transition ensures the library is capable of handling valid edge cases, such as negative interest rates, without throwing errors. By relying on a supported library, the application avoids vulnerabilities associated with outdated dependencies, ensuring stability and security.

In the mitigated PHP code, the CalcPro library is used instead of the deprecated NumCalc. The CalcPro library actively addresses issues and provides support for edge cases like negative interest rates. Unlike the original vulnerable example, this code benefits from the reliability and security of a maintained dependency, ensuring accurate and predictable functionality.

The mitigated C# code transitions from NumCalc to the actively maintained CalcPro library. This change resolves the issue of unhandled edge cases, as CalcPro includes robust error handling and ongoing support. The code is now secure because it no longer relies on an unsupported library, ensuring consistent performance and compatibility with evolving system requirements.

The updated Java code uses CalcPro instead of the outdated NumCalc. By switching to a library with active support and updates, the code now handles edge cases such as negative interest rates effectively. This mitigated approach eliminates the vulnerability of relying on an unmaintained library and ensures continued reliability and security for the application.

The mitigated C++ code replaces NumCalc with CalcPro, an actively maintained library that ensures proper handling of edge cases like negative interest rates. This change removes the reliance on an unsupported dependency, significantly improving security and reliability. The application can now depend on CalcPro for consistent performance and timely updates, avoiding the pitfalls of the vulnerable example.

Here are some additional resources to expand your understanding of unmaintained software risks and mitigation strategies:

• OWASP Open Source Software Top 10
• Snyk Vulnerability Database – Explore a comprehensive database of known vulnerabilities in various libraries and frameworks.
• Adoptoposs – A platform to find or adopt unmaintained open-source projects.