CVE-2018-18282 in Next.js
Summary
by MITRE
Next.js 7.0.0 and 7.0.1 has XSS via the 404 or 500 /_error page.
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Analysis
by VulDB Data Team • 05/25/2023
The vulnerability CVE-2018-18282 represents a cross-site scripting weakness in Next.js versions 7.0.0 and 7.0.1 that specifically affects the error handling mechanism of the framework. This issue manifests through the rendering of 404 and 500 error pages, which are automatically generated by Next.js when encountering missing resources or server-side errors. The vulnerability occurs because the framework fails to properly sanitize user input that gets incorporated into these error pages, creating an opportunity for malicious actors to inject arbitrary JavaScript code that executes in the context of other users' browsers.
The technical flaw stems from inadequate input validation and output encoding within Next.js's default error page rendering logic. When a user navigates to a non-existent page or when a server error occurs, Next.js automatically displays a standardized error page at the /_error route. However, certain parameters or URL segments that are passed to these error pages are not properly escaped or filtered before being rendered to the browser. This creates a classic XSS vulnerability where attacker-controlled data can be injected into the HTML output, particularly when the error page displays information about the requested URL or query parameters.
The operational impact of this vulnerability is significant for applications built with Next.js 7.0.0 or 7.0.1, as it allows remote attackers to execute malicious scripts in the browsers of other users who encounter the error page. This could enable session hijacking, credential theft, defacement of web applications, or redirection to malicious sites. The vulnerability is particularly dangerous because error pages are often visited by users who may not be actively browsing the application, making the attack surface broader than typical user-facing functionality. Attackers could craft malicious URLs that, when accessed by other users, would trigger the vulnerable error page and execute their payload.
Organizations using affected versions of Next.js should immediately upgrade to version 7.0.2 or later where this vulnerability has been patched. The fix involves implementing proper HTML escaping and input sanitization for all data that gets rendered in the error pages, ensuring that any user-provided input is treated as untrusted and properly encoded before being displayed. Security teams should also conduct a comprehensive review of their error handling mechanisms and ensure that all user input is validated and sanitized before being incorporated into any dynamic content. This vulnerability aligns with CWE-79 which specifically addresses cross-site scripting flaws, and represents a typical example of how improper input validation can lead to severe security consequences. From an ATT&CK perspective, this vulnerability maps to T1203 - Exploitation for Client Execution, as it enables attackers to execute malicious code in victim browsers through the exploitation of error handling mechanisms.