CVE-2023-3965 in nsc Plugin
Summary
by MITRE • 10/25/2023
The nsc theme for WordPress is vulnerable to Reflected Cross-Site Scripting via prototype pollution in versions up to, and including, 1.0 due to insufficient input sanitization and output escaping. This makes it possible for unauthenticated attackers to inject arbitrary web scripts in pages that execute if they can successfully trick a user into performing an action such as clicking on a link.
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Analysis
by VulDB Data Team • 04/10/2026
The nsc theme for WordPress represents a significant security vulnerability classified as CVE-2023-3965, which manifests as a reflected cross-site scripting vulnerability through prototype pollution. This weakness affects versions up to and including 1.0 of the theme, creating a persistent threat vector that can be exploited by unauthenticated attackers. The vulnerability stems from inadequate input sanitization and insufficient output escaping mechanisms within the theme's codebase, allowing malicious actors to inject arbitrary web scripts that execute when users interact with compromised pages. The prototype pollution aspect of this vulnerability is particularly concerning as it leverages JavaScript's prototype chain manipulation to introduce malicious code into the application's execution environment. This vulnerability operates under the CWE-79 classification for cross-site scripting, specifically targeting reflected XSS scenarios where attacker-controlled data is immediately reflected back in the application's response without proper sanitization. The ATT&CK framework categorizes this as a web application vulnerability exploitation technique that can lead to user session hijacking, credential theft, and further privilege escalation within the WordPress environment.
The technical implementation of this vulnerability occurs when the nsc theme fails to properly validate and sanitize user input parameters before processing them within the WordPress framework. The prototype pollution mechanism allows attackers to manipulate the Object.prototype properties, which can then be exploited to execute malicious JavaScript code in the context of the victim's browser. When users navigate to pages that utilize the vulnerable theme and encounter the maliciously injected script, the payload executes automatically without requiring any additional user interaction beyond visiting the compromised page. This makes the attack particularly dangerous as it can be delivered through various vectors including malicious links, social engineering campaigns, or compromised advertisements that direct users to vulnerable WordPress installations. The reflected nature of the vulnerability means that the malicious script is immediately reflected back to the user's browser through the web application's response, bypassing traditional security measures that might otherwise detect persistent malicious code.
The operational impact of CVE-2023-3965 extends beyond simple script injection, creating potential pathways for more sophisticated attacks within the WordPress ecosystem. Unauthenticated attackers can leverage this vulnerability to execute arbitrary commands on behalf of authenticated users, potentially leading to complete compromise of WordPress installations. The vulnerability affects not only the specific theme but can also impact other components that rely on the same prototype pollution vectors, creating cascading security implications throughout the application stack. Attackers can use this weakness to steal user credentials, manipulate content, redirect users to malicious sites, or establish persistent backdoors within the WordPress environment. The lack of authentication requirements for exploitation makes this vulnerability particularly dangerous as it can be exploited by anyone with access to the internet, regardless of their technical expertise or authorization level within the target organization. This vulnerability directly impacts the integrity and availability of WordPress websites, potentially causing data breaches, service disruption, and reputational damage to organizations relying on the affected theme.
Mitigation strategies for CVE-2023-3965 require immediate action to address the prototype pollution vulnerability within the nsc theme. Organizations should upgrade to the latest version of the theme if available, or implement comprehensive input validation and output escaping mechanisms to prevent malicious script injection. The recommended approach includes implementing strict sanitization of all user inputs, particularly those that are reflected in web responses, and ensuring that the theme properly escapes output before rendering content. Security measures should also include monitoring for suspicious user agent strings, implementing content security policies, and deploying web application firewalls to detect and block malicious payloads. Regular security audits of WordPress themes and plugins are essential to identify similar vulnerabilities that may exist in other components of the web application stack. Additionally, administrators should consider implementing principle of least privilege access controls, regular security updates, and comprehensive backup strategies to ensure rapid recovery in case of successful exploitation attempts. The vulnerability highlights the importance of proper input validation and output escaping practices as outlined in the OWASP Top Ten security framework, emphasizing that all user-supplied data must be treated as potentially malicious and properly sanitized before processing or display.