CVE-2025-56200: validator.js URL Validation Bypass Vulnerability
Summary
CVE-2025-56200: validator.js has a URL validation bypass vulnerability in its isURL function. Affects validator versions < 13.15.15. No fix is published. How to fix ↓
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Background
validator.js is a popular library used in Node.js applications for validating and sanitizing strings, particularly URLs, emails, and other formats. It provides developers with a robust set of tools to ensure that user input is safe and conforms to expected formats. However, a vulnerability has been identified in the isURL function of validator.js, which can lead to security risks if not addressed.
Vulnerability Detail
A URL validation bypass vulnerability exists in validator.js through version 13.15.15. The isURL() function incorrectly uses '://' as a delimiter to parse protocols, while browsers utilize ':' as the delimiter. This discrepancy allows attackers to craft malicious URLs that can bypass protocol and domain validation, potentially leading to Cross-Site Scripting (XSS) and Open Redirect attacks. The vulnerability is classified under CWE-79, indicating its relation to improper input validation.
How To Fix
No fixed version is published for this vulnerability.
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Workaround
As a temporary workaround, you can implement additional validation checks in your application to ensure that URLs conform to expected formats. For example, you can use regular expressions to validate URLs before processing them. Here’s a simple example in JavaScript:
const isValidURL = (url) => {
const regex = /^(https?:\/\/)?([\w.-]+)(:[0-9]{1,5})?(\/.*)?$/;
return regex.test(url);
};
// Usage
if (isValidURL(userInputURL)) {
// Proceed with the URL
} else {
// Handle invalid URL
}
Conclusion
The validator.js URL validation bypass vulnerability (CVE-2025-56200) poses a significant risk to applications using the affected versions of the library. It is crucial for developers to update to the latest version to protect against potential attacks. Additionally, implementing temporary workarounds can help mitigate risks until the update is applied.
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FAQ
CVE-2025-56200 is a vulnerability in the validator.js library that allows attackers to bypass URL validation, potentially leading to security issues like XSS and Open Redirect attacks.
The vulnerability affects all versions of validator.js up to and including version 13.15.15.
You can use Vulert, which monitors and alerts for open-source vulnerabilities in real-time. You can check your application by uploading your package-lock.json file or using the Vulert playground without signup.
The CVSS score of this vulnerability is 6.1, indicating a moderate level of risk.
If you cannot update the package right away, implement additional validation checks in your application to mitigate the risk until you can apply the patch.
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