CVE-2016-10934 in check-email Plugin
Summary
by MITRE
The check-email plugin before 0.5.2 for WordPress has XSS.
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Analysis
by VulDB Data Team • 12/04/2023
The CVE-2016-10934 vulnerability represents a cross-site scripting flaw in the check-email plugin for WordPress systems prior to version 0.5.2. This vulnerability resides within a widely used WordPress plugin that performs email validation checks, making it a significant concern for WordPress administrators and security professionals. The issue stems from inadequate input sanitization and output encoding practices within the plugin's codebase, creating an exploitable condition that allows malicious actors to inject arbitrary JavaScript code into web pages viewed by other users.
The technical implementation of this vulnerability occurs when the plugin processes user-supplied email addresses without proper sanitization of special characters and HTML entities. Attackers can craft malicious email addresses containing script tags or other XSS payloads that get executed in the context of other users' browsers when the plugin displays these addresses. This flaw typically manifests when the plugin's email validation function fails to properly escape or encode user input before rendering it in HTML contexts, creating a classic reflected XSS attack vector. The vulnerability is particularly concerning because it operates at the plugin level rather than within core WordPress functionality, making it harder to detect through standard security scanning tools.
The operational impact of this vulnerability extends beyond simple script execution, as it can enable attackers to perform session hijacking, deface websites, steal sensitive cookies, or redirect users to malicious domains. WordPress administrators who have not updated to version 0.5.2 or later remain at risk, as the vulnerability affects the plugin's ability to properly validate and display email addresses in various user interfaces. The attack surface is broad since many WordPress sites utilize email validation plugins for user registration, contact forms, or administrative functions, increasing the potential exposure for affected systems. This vulnerability aligns with CWE-79, which specifically addresses cross-site scripting flaws in software applications, and can be categorized under ATT&CK technique T1566 for initial access through malicious email.
Mitigation strategies for CVE-2016-10934 require immediate action from WordPress administrators to upgrade to the patched version 0.5.2 or later of the check-email plugin. Security teams should implement comprehensive plugin inventory management to identify all vulnerable installations across their WordPress infrastructure. Additional protective measures include implementing content security policies that restrict script execution, enabling proper input validation at multiple layers, and conducting regular security audits of third-party WordPress plugins. Organizations should also consider implementing web application firewalls to detect and block known XSS attack patterns, while maintaining regular monitoring for suspicious activity related to email validation functions. The vulnerability demonstrates the critical importance of keeping WordPress plugins updated and following security best practices for input validation and output encoding as recommended by the OWASP Top Ten project and NIST cybersecurity guidelines.