CVE-2025-31578: Fonts Manager Custom Fonts XSS Vulnerability

CVE-2025-31578 Overview

CVE-2025-31578 is a Reflected Cross-Site Scripting (XSS) vulnerability affecting the Fonts Manager | Custom Fonts WordPress plugin developed by Wisdomlogix Solutions Pvt. Ltd. This vulnerability arises from improper neutralization of user-supplied input during web page generation, allowing attackers to inject malicious scripts that execute in the context of a victim's browser session.

Critical Impact

Attackers can exploit this Reflected XSS vulnerability to steal session cookies, hijack user accounts, redirect users to malicious websites, or perform unauthorized actions on behalf of authenticated WordPress administrators.

Affected Products

• Fonts Manager | Custom Fonts WordPress Plugin versions up to and including 1.2
• WordPress installations running vulnerable versions of the fonts-manager-custom-fonts plugin

Discovery Timeline

• 2025-04-01 - CVE-2025-31578 published to NVD
• 2026-04-15 - Last updated in NVD database

Technical Details for CVE-2025-31578

Vulnerability Analysis

This vulnerability is classified as CWE-79 (Improper Neutralization of Input During Web Page Generation), commonly known as Cross-Site Scripting. The Fonts Manager | Custom Fonts plugin fails to properly sanitize and escape user-controlled input before reflecting it back in the HTTP response. When a victim clicks a maliciously crafted link or is redirected to a specially crafted URL, the injected script executes within their browser context with the same privileges as the legitimate application.

Reflected XSS vulnerabilities in WordPress plugins are particularly dangerous because they can target site administrators with elevated privileges. Successful exploitation could allow attackers to create rogue admin accounts, modify site content, install backdoors, or exfiltrate sensitive configuration data.

Root Cause

The root cause of this vulnerability is insufficient input validation and output encoding in the Fonts Manager | Custom Fonts plugin. User-supplied data passed through URL parameters or form fields is not properly sanitized before being included in the HTML response. The plugin lacks the necessary security controls such as escaping special characters (<, >, ", ', &) or implementing Content Security Policy headers that would prevent script injection.

Attack Vector

This is a Reflected XSS attack that requires social engineering to be successful. An attacker crafts a malicious URL containing JavaScript payload targeting the vulnerable plugin endpoint. The attack flow typically involves:

1. The attacker identifies a vulnerable parameter in the Fonts Manager plugin
2. A malicious URL is crafted with embedded JavaScript in the vulnerable parameter
3. The victim (typically a WordPress administrator) is tricked into clicking the malicious link via phishing email, social media, or compromised websites
4. The victim's browser executes the injected script in the context of the WordPress admin session
5. The attacker can then steal session tokens, perform CSRF attacks, or execute administrative actions

Since no verified code examples are available for this vulnerability, users should refer to the Patchstack Vulnerability Analysis for detailed technical information about the specific injection points and attack methodology.

Detection Methods for CVE-2025-31578

Indicators of Compromise

• Unusual URL patterns in web server logs containing encoded JavaScript payloads targeting /wp-content/plugins/fonts-manager-custom-fonts/ paths
• Reports from users about suspicious redirects or unexpected behavior after clicking links to your WordPress site
• Unexpected modifications to WordPress user accounts or site settings without legitimate admin activity
• JavaScript errors in browser consoles related to the fonts-manager-custom-fonts plugin

Detection Strategies

• Implement Web Application Firewall (WAF) rules to detect and block common XSS attack patterns in URL parameters
• Enable detailed logging for WordPress plugin activity and monitor for suspicious request patterns
• Deploy browser-based XSS detection tools that can identify reflected script execution
• Use SentinelOne Singularity to monitor endpoint behavior for signs of session hijacking or credential theft following XSS exploitation

Monitoring Recommendations

• Review web server access logs for requests containing suspicious characters like <script>, javascript:, or encoded variants targeting plugin endpoints
• Configure alerting for failed or anomalous authentication attempts following visits to plugin-related URLs
• Monitor for unexpected outbound network connections from user browsers that may indicate data exfiltration
• Implement Content Security Policy (CSP) violation reporting to detect XSS attempts in real-time

How to Mitigate CVE-2025-31578

Immediate Actions Required

• Update the Fonts Manager | Custom Fonts plugin to a patched version as soon as one becomes available from the vendor
• Consider temporarily deactivating the fonts-manager-custom-fonts plugin until a security patch is released
• Implement a Web Application Firewall (WAF) with XSS protection rules to filter malicious requests
• Educate WordPress administrators about the risks of clicking suspicious links, especially those targeting the WordPress admin area

Patch Information

Check the Patchstack Vulnerability Analysis for the latest patch status and remediation guidance. Users running version 1.2 or earlier should update immediately when a patched version is released by Wisdomlogix Solutions Pvt. Ltd.

Workarounds

• Temporarily disable the Fonts Manager | Custom Fonts plugin if it is not critical to site functionality
• Implement strict Content Security Policy (CSP) headers to prevent inline script execution
• Use WordPress security plugins that provide real-time XSS attack detection and blocking capabilities
• Restrict access to the WordPress admin area by IP address whitelist where feasible

# WordPress .htaccess hardening - Add CSP header to mitigate XSS
<IfModule mod_headers.c>
    Header set Content-Security-Policy "default-src 'self'; script-src 'self'; style-src 'self' 'unsafe-inline';"
    Header set X-XSS-Protection "1; mode=block"
    Header set X-Content-Type-Options "nosniff"
</IfModule>