CVE-2025-64718: Fix Js-yaml Prototype Pollution Vulnerability

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CVE-2025-64718: js-yaml Vulnerability and Mitigation

Hey guys, let's dive into a security issue that's been identified in the js-yaml library. It's crucial to stay informed about these vulnerabilities to keep our applications secure. This article breaks down the CVE-2025-64718 vulnerability, its impact, and how to fix it. So, let's get started!

What is CVE-2025-64718?

CVE-2025-64718 is a medium severity vulnerability found in js-yaml-3.14.1.tgz. This vulnerability allows for prototype pollution, which can have significant security implications if not addressed promptly. Prototype pollution occurs when an attacker can manipulate the properties of JavaScript object prototypes, potentially leading to unexpected behavior or even code execution.

Vulnerable Library: js-yaml-3.14.1.tgz

  • Description: js-yaml is a JavaScript YAML parser and serializer.
  • Library Home Page: https://registry.npmjs.org/js-yaml/-/js-yaml-3.14.1.tgz
  • Dependency File Path: /framework/images/webapp/images/jquery/plugins/validate/package.json
  • Vulnerable Library Path: /framework/images/webapp/images/jquery/plugins/validate/node_modules/js-yaml/package.json
  • Base Branch: trunk

Dependency Hierarchy

The vulnerability exists within a specific dependency chain:

- grunt-0.3.17.tgz (Root Library)
  - nodeunit-0.7.4.tgz
    - tap-15.0.9.tgz
      - coveralls-3.1.0.tgz
        - js-yaml-3.14.1.tgz (Vulnerable Library)

Understanding this hierarchy helps in tracing the vulnerability back to its origin and identifying all the components that might be affected. Make sure to check your project's dependencies to see if you're using a vulnerable version of js-yaml.

Vulnerability Details

The core issue lies in the possibility of an attacker modifying the prototype of a parsed YAML document via prototype pollution using the __proto__ property. This is particularly concerning when parsing untrusted YAML documents, as it can lead to various security exploits.

The vulnerability was reported and patched in js-yaml version 4.1.1. It's highly recommended to upgrade to this version or later to mitigate the risk.

Impact of Prototype Pollution

Prototype pollution can have serious consequences. If an attacker successfully pollutes the prototype, they can:

  1. Modify Object Behavior: Change the default behavior of objects in the application, leading to unexpected results.
  2. Denial of Service (DoS): Cause the application to crash or become unresponsive.
  3. Security Bypass: Circumvent security checks and gain unauthorized access to sensitive data.
  4. Remote Code Execution (RCE): In some cases, it might even be possible to execute arbitrary code on the server.

To reduce the attack surface, utilize runtime flags like --disable-proto=delete in Node.js or use Deno, which has built-in pollution protection.

CVSS 3.0 Score Details

The Common Vulnerability Scoring System (CVSS) provides a standardized way to assess the severity of security vulnerabilities. For CVE-2025-64718, the CVSS 3.0 score is 5.3, indicating a medium severity.

Base Score Metrics

  • Exploitability Metrics:
    • Attack Vector: Network
    • Attack Complexity: Low
    • Privileges Required: None
    • User Interaction: None
    • Scope: Unchanged
  • Impact Metrics:
    • Confidentiality Impact: None
    • Integrity Impact: Low
    • Availability Impact: None

Understanding the CVSS Score

The CVSS score helps prioritize vulnerability management efforts. A score of 5.3 means the vulnerability is exploitable over the network with low complexity and without requiring any privileges or user interaction. While it doesn't directly impact confidentiality or availability, it can compromise the integrity of the application.

For more detailed information on CVSS3 Scores, you can refer to the CVSS Calculator.

Suggested Fix: Upgrade js-yaml

The recommended solution is to upgrade to js-yaml version 4.1.1 or later. This version includes a patch that addresses the prototype pollution vulnerability.

How to Upgrade

Depending on your project's package manager, you can use the following commands to upgrade js-yaml:

  • npm:

    npm install js-yaml@latest

  • Yarn:

    yarn upgrade js-yaml@latest

After running the upgrade command, make sure to test your application thoroughly to ensure that the new version of js-yaml doesn't introduce any compatibility issues.

Additional Mitigation Strategies

Besides upgrading js-yaml, consider these additional security measures:

  1. Input Validation: Always validate and sanitize YAML input to prevent malicious data from being processed.
  2. Runtime Protection: Use runtime flags like --disable-proto=delete in Node.js to disable prototype modifications.
  3. Content Security Policy (CSP): Implement CSP headers to restrict the execution of untrusted code in the browser.
  4. Regular Security Audits: Conduct regular security audits to identify and address potential vulnerabilities in your application.

Conclusion

Keeping your dependencies up-to-date is crucial for maintaining the security of your applications. The CVE-2025-64718 vulnerability in js-yaml-3.14.1.tgz is a prime example of why it's important to stay informed and proactive. By upgrading to js-yaml version 4.1.1 or later, you can effectively mitigate the risk of prototype pollution and protect your application from potential attacks.

Remember, security is an ongoing process. Always be vigilant and take the necessary steps to secure your applications. Stay safe out there, guys!