CVE-2025-25099: Appointment Buddy Widget XSS Vulnerability

CVE-2025-25099 Overview

CVE-2025-25099 is a Cross-Site Scripting (XSS) vulnerability identified in the Appointment Buddy Widget WordPress plugin developed by accreteinfosolution. The vulnerability stems from improper neutralization of user-supplied input during web page generation, allowing attackers to inject malicious scripts into web pages viewed by other users.

This XSS vulnerability in the appointment-buddy-online-appointment-booking-by-accrete plugin can enable attackers to execute arbitrary JavaScript code in the context of a victim's browser session. Successful exploitation could lead to session hijacking, credential theft, defacement of web pages, or redirection of users to malicious sites.

Critical Impact

Attackers can inject malicious scripts that execute in the context of authenticated user sessions, potentially compromising WordPress administrator accounts and gaining full control of affected websites.

Affected Products

• Appointment Buddy Widget plugin for WordPress versions through 1.2
• WordPress installations utilizing the Appointment Buddy Online Appointment Booking plugin
• Websites using vulnerable versions of appointment-buddy-online-appointment-booking-by-accrete

Discovery Timeline

• 2025-03-03 - CVE-2025-25099 published to NVD
• 2026-04-15 - Last updated in NVD database

Technical Details for CVE-2025-25099

Vulnerability Analysis

This vulnerability is classified as CWE-79 (Improper Neutralization of Input During Web Page Generation), commonly known as Cross-Site Scripting. The Appointment Buddy Widget plugin fails to properly sanitize and escape user-controlled input before rendering it in the browser, allowing injection of malicious script content.

XSS vulnerabilities in WordPress plugins are particularly dangerous because they can be leveraged to target site administrators. When an administrator views a page containing injected malicious code, the attacker's script executes with the administrator's privileges, potentially allowing full site compromise.

The vulnerability affects all versions of the plugin from the initial release through version 1.2.

Root Cause

The root cause of this vulnerability lies in insufficient input validation and output encoding within the Appointment Buddy Widget plugin. The plugin processes user-supplied data and renders it in HTML output without properly escaping special characters that have significance in HTML/JavaScript contexts.

WordPress provides built-in escaping functions such as esc_html(), esc_attr(), and wp_kses() that should be used to sanitize output. The vulnerable code paths in this plugin appear to bypass or inadequately implement these security controls, allowing attackers to break out of the intended data context and inject executable script code.

Attack Vector

The attack vector for this XSS vulnerability involves an attacker crafting malicious input containing JavaScript code and submitting it through the plugin's appointment booking functionality. When this unsanitized input is subsequently displayed to other users or administrators, the malicious script executes in their browser context.

Depending on the specific injection point, this could be a stored XSS (persistent) or reflected XSS attack. Stored XSS attacks are particularly severe as the malicious payload persists in the application's database and affects all users who view the compromised content.

For technical details on the vulnerability mechanism, refer to the Patchstack Vulnerability Report.

Detection Methods for CVE-2025-25099

Indicators of Compromise

• Unexpected JavaScript code or <script> tags appearing in appointment booking forms or plugin output
• User reports of browser warnings, unexpected redirects, or suspicious pop-ups when accessing booking pages
• Anomalous outbound connections from client browsers to unknown external domains
• Modifications to user session cookies or authentication tokens
• Unusual administrative actions performed without administrator knowledge

Detection Strategies

• Implement Web Application Firewall (WAF) rules to detect and block common XSS payloads in HTTP requests
• Monitor server access logs for requests containing suspicious patterns such as <script>, javascript:, or encoded variants
• Deploy Content Security Policy (CSP) headers and monitor violation reports for injection attempts
• Conduct regular security scans of WordPress installations using vulnerability scanners that check plugin versions

Monitoring Recommendations

• Enable WordPress debug logging and review for unexpected plugin behavior or errors
• Configure real-time alerting for changes to plugin files or database entries related to the Appointment Buddy Widget
• Monitor for new user account creation or privilege escalation that could indicate post-exploitation activity
• Implement browser-side XSS auditing and CSP reporting to detect exploitation attempts

How to Mitigate CVE-2025-25099

Immediate Actions Required

• Deactivate the Appointment Buddy Widget plugin immediately if running version 1.2 or earlier
• Review WordPress user accounts for any unauthorized administrative accounts or privilege changes
• Check for signs of compromise including modified plugin files, unexpected database entries, or unauthorized content
• Implement a Web Application Firewall (WAF) with XSS protection rules as a temporary mitigation

Patch Information

Check for an updated version of the Appointment Buddy Widget plugin that addresses this vulnerability. Visit the WordPress plugin repository or the vendor's official website for the latest security updates. If no patched version is available, consider replacing the plugin with a secure alternative.

Review the Patchstack Vulnerability Report for additional information on remediation options.

Workarounds

• Disable the vulnerable plugin until a security patch is released by the vendor
• Implement strict Content Security Policy (CSP) headers to mitigate the impact of XSS attacks
• Use a WordPress security plugin with virtual patching capabilities to block exploitation attempts
• Restrict access to the appointment booking functionality to authenticated users only if feasible

# Add Content Security Policy header to Apache configuration
# Add to .htaccess or Apache virtual host configuration
Header set Content-Security-Policy "default-src 'self'; script-src 'self'; style-src 'self' 'unsafe-inline';"

# For Nginx, add to server block
# add_header Content-Security-Policy "default-src 'self'; script-src 'self'; style-src 'self' 'unsafe-inline';";