CVE-2025-46510: Contact Form 7 Calendar CSRF Vulnerability

CVE-2025-46510 Overview

CVE-2025-46510 is a Cross-Site Request Forgery (CSRF) vulnerability in the Contact Form 7 Calendar WordPress plugin (cf7-calendar) developed by harrysudana. This vulnerability allows attackers to chain CSRF with Stored Cross-Site Scripting (XSS), enabling malicious actors to inject persistent scripts into the vulnerable application by tricking authenticated administrators into performing unintended actions.

Critical Impact

Successful exploitation allows attackers to inject malicious scripts that persist in the application, potentially leading to session hijacking, credential theft, administrative account compromise, and website defacement affecting all visitors.

Affected Products

• Contact Form 7 Calendar WordPress Plugin versions up to and including 3.0.1
• WordPress installations using the cf7-calendar plugin
• Websites with Contact Form 7 integration utilizing the Calendar addon

Discovery Timeline

• 2025-04-24 - CVE-2025-46510 published to NVD
• 2026-04-15 - Last updated in NVD database

Technical Details for CVE-2025-46510

Vulnerability Analysis

This vulnerability combines two distinct attack vectors: Cross-Site Request Forgery (CSRF) and Stored Cross-Site Scripting (XSS). The plugin fails to implement proper CSRF token validation on administrative forms, allowing attackers to craft malicious requests that, when executed by an authenticated administrator, inject persistent malicious JavaScript code into the plugin's settings or calendar entries.

The chained nature of this vulnerability significantly increases its impact. The initial CSRF component bypasses the same-origin policy protection by exploiting the absence of anti-CSRF tokens, while the subsequent Stored XSS payload persists in the database and executes in the browsers of all users who view the affected pages.

Root Cause

The root cause of this vulnerability stems from two critical security oversights in the Contact Form 7 Calendar plugin:

1. Missing CSRF Protection: Administrative forms within the plugin do not implement WordPress nonce verification, allowing attackers to forge requests that appear to originate from legitimate administrators.

2. Inadequate Input Sanitization: User-supplied input is not properly sanitized before being stored in the database, nor is it escaped when rendered in the browser, enabling the injection of malicious script content.

The combination of these flaws creates a dangerous attack chain where an attacker can force an administrator to unknowingly inject malicious code that will then execute for all subsequent visitors to the affected pages.

Attack Vector

The attack typically unfolds in the following manner:

1. An attacker crafts a malicious HTML page containing a hidden form that submits data to the vulnerable plugin's administrative endpoints
2. The form includes XSS payloads embedded in input fields that will be stored by the plugin
3. The attacker lures an authenticated WordPress administrator to visit the malicious page
4. Upon page load, the form automatically submits via JavaScript, leveraging the administrator's active session
5. The plugin processes the request without CSRF validation and stores the malicious payload
6. When any user visits pages displaying the calendar or plugin output, the stored XSS payload executes in their browser

The vulnerability requires user interaction (an admin must visit the attacker's page) but requires no authentication from the attacker's perspective. For more technical details, refer to the Patchstack Security Vulnerability Report.

Detection Methods for CVE-2025-46510

Indicators of Compromise

• Unexpected JavaScript code or <script> tags appearing in Contact Form 7 Calendar settings or database entries
• Suspicious administrative actions in WordPress audit logs that the administrator does not recall performing
• Reports of browser security warnings or unexpected redirects from visitors viewing calendar pages
• New or modified calendar entries containing encoded script content or event handlers

Detection Strategies

• Review WordPress database tables associated with the cf7-calendar plugin for suspicious HTML/JavaScript content
• Monitor HTTP access logs for POST requests to plugin endpoints from referrers outside your domain
• Implement Content Security Policy (CSP) headers and monitor violation reports for script injection attempts
• Deploy web application firewall (WAF) rules to detect and block CSRF and XSS attack patterns

Monitoring Recommendations

• Enable comprehensive WordPress activity logging to track all administrative changes
• Configure real-time alerts for modifications to plugin settings or calendar data
• Implement file integrity monitoring to detect unauthorized changes to plugin files
• Monitor for outbound connections from visitor browsers that may indicate XSS payload execution

How to Mitigate CVE-2025-46510

Immediate Actions Required

• Update the Contact Form 7 Calendar plugin to a patched version when available from the developer
• If no patch is available, consider temporarily deactivating the plugin until a fix is released
• Review and audit existing calendar entries and plugin settings for signs of malicious content
• Instruct administrators to avoid clicking links from untrusted sources while logged into WordPress

Patch Information

Organizations should monitor the official WordPress plugin repository and the Patchstack Security Advisory for updates regarding patched versions. Until an official patch is released, implementing the workarounds below is strongly recommended.

Workarounds

• Temporarily disable the Contact Form 7 Calendar plugin if it is not critical to operations
• Implement a Web Application Firewall (WAF) with rules to block CSRF and XSS attack patterns
• Add manual nonce verification by using a security plugin that enforces CSRF protection across all admin forms
• Restrict administrative access to trusted IP addresses to reduce the attack surface

# WordPress wp-config.php hardening example
# Add these lines to help mitigate unauthorized administrative access

# Force SSL for admin
define('FORCE_SSL_ADMIN', true);

# Disable file editing in admin panel
define('DISALLOW_FILE_EDIT', true);

# Limit login attempts (requires additional plugin)
# Consider using Limit Login Attempts Reloaded or similar