CVE-2025-23724: University Quizzes Online XSS Vulnerability

CVE-2025-23724 Overview

CVE-2025-23724 is a Reflected Cross-Site Scripting (XSS) vulnerability discovered in the University Quizzes Online WordPress plugin developed by oleksandr87. This vulnerability stems from improper neutralization of input during web page generation, allowing attackers to inject malicious scripts that execute in the context of a victim's browser session.

The vulnerability affects all versions of the University Quizzes Online plugin through version 1.4. When exploited, an attacker can craft malicious URLs containing JavaScript payloads that, when clicked by an authenticated user, execute arbitrary scripts in their browser context.

Critical Impact

Attackers can steal session cookies, redirect users to malicious sites, deface web pages, or perform actions on behalf of authenticated users including administrators.

Affected Products

• University Quizzes Online WordPress Plugin versions up to and including 1.4
• WordPress installations running the vulnerable plugin versions

Discovery Timeline

• 2025-01-23 - CVE-2025-23724 published to NVD
• 2026-04-23 - Last updated in NVD database

Technical Details for CVE-2025-23724

Vulnerability Analysis

This Reflected XSS vulnerability (CWE-79) occurs when the University Quizzes Online plugin fails to properly sanitize user-supplied input before reflecting it back in the HTTP response. The plugin does not adequately encode or escape special characters in user input, allowing HTML and JavaScript code to be injected into the rendered page.

In a reflected XSS attack, the malicious payload is embedded in a request parameter and immediately reflected back to the user in the server's response. The attack requires user interaction—typically clicking a crafted link—but can have significant impact once executed.

The scope of this vulnerability extends beyond the vulnerable component itself, potentially affecting other origins or security contexts within the user's browser session. This characteristic makes the vulnerability particularly dangerous in multi-tenant WordPress environments.

Root Cause

The root cause of CVE-2025-23724 is the absence of proper input validation and output encoding within the University Quizzes Online plugin. User-controlled data is included in the HTML response without being sanitized through functions like esc_html(), esc_attr(), or wp_kses() that WordPress provides for preventing XSS attacks.

WordPress plugins must implement defense-in-depth by validating input on receipt and encoding output when rendering to ensure that any special characters are treated as data rather than executable code.

Attack Vector

The attack vector for this vulnerability is network-based, requiring user interaction. An attacker crafts a malicious URL containing JavaScript payload in a vulnerable parameter of the University Quizzes Online plugin. The attack flow typically follows this pattern:

1. Attacker identifies a vulnerable endpoint in the plugin that reflects user input
2. Attacker constructs a URL with malicious JavaScript embedded in a parameter
3. Attacker distributes the malicious URL via phishing emails, social media, or other channels
4. Victim clicks the link while authenticated to the WordPress site
5. The malicious script executes in the victim's browser with their session context
6. Attacker can steal cookies, perform CSRF attacks, or harvest credentials

The vulnerability can be exploited to target administrators, potentially leading to full site compromise through privilege escalation or plugin/theme injection.

Detection Methods for CVE-2025-23724

Indicators of Compromise

• Unusual URL parameters in web server access logs containing encoded JavaScript payloads (e.g., %3Cscript%3E, javascript:, onerror=)
• Reports from users about unexpected redirects or pop-ups when accessing quiz-related pages
• Browser console errors or unexpected script execution on pages served by the University Quizzes Online plugin
• Web Application Firewall (WAF) alerts for XSS patterns targeting WordPress plugin endpoints

Detection Strategies

• Enable and review WordPress audit logs for suspicious activity on quiz-related endpoints
• Implement WAF rules to detect and block common XSS payloads in URL parameters
• Deploy browser-based security headers including Content-Security-Policy (CSP) to limit script execution
• Conduct regular vulnerability scanning of WordPress installations using tools that check for known plugin vulnerabilities

Monitoring Recommendations

• Monitor web server logs for requests containing suspicious characters or encoded payloads targeting the university-quizzes-online plugin paths
• Set up alerts for high-volume requests to plugin endpoints that may indicate automated exploitation attempts
• Review referrer headers for unusual external sources directing traffic to quiz pages
• Implement real-time threat intelligence feeds that include WordPress plugin vulnerability data

How to Mitigate CVE-2025-23724

Immediate Actions Required

• Deactivate the University Quizzes Online plugin immediately until a patched version is available
• Review WordPress user accounts for unauthorized access or privilege changes
• Audit recent access logs for signs of exploitation attempts
• Implement Content-Security-Policy headers to restrict inline script execution
• Consider using a WordPress security plugin or WAF to provide virtual patching

Patch Information

At the time of publication, administrators should monitor the Patchstack Vulnerability Report for updates on patch availability. Users should update to a patched version as soon as one is released by the plugin developer.

Workarounds

• Disable the University Quizzes Online plugin until a security patch is available
• Implement strict Content-Security-Policy headers that prevent inline JavaScript execution
• Use a Web Application Firewall (WAF) with XSS filtering rules to block malicious payloads
• Restrict plugin access to trusted users only through WordPress user role management
• Consider using alternative quiz plugins that have been audited for security vulnerabilities

# WordPress CLI command to deactivate the vulnerable plugin
wp plugin deactivate university-quizzes-online

# Add Content-Security-Policy header in .htaccess (Apache)
# Header set Content-Security-Policy "default-src 'self'; script-src 'self'; object-src 'none';"