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

CVE-2025-31578 Overview

CVE-2025-31578 is a reflected Cross-Site Scripting (XSS) vulnerability in the Wisdomlogix Solutions Fonts Manager | Custom Fonts WordPress plugin. The flaw affects all versions of fonts-manager-custom-fonts from initial release through version 1.2. The vulnerability stems from improper neutralization of user-supplied input during web page generation [CWE-79]. Attackers can craft malicious URLs that, when visited by an authenticated or unauthenticated user, execute arbitrary JavaScript in the victim's browser session. The scope-changed CVSS vector indicates that successful exploitation can impact resources beyond the vulnerable component, including the WordPress administrative interface.

Critical Impact

Successful exploitation allows attackers to execute arbitrary scripts in a victim's browser, potentially hijacking sessions, stealing credentials, or performing administrative actions on the WordPress site.

Affected Products

• Wisdomlogix Solutions Pvt. Ltd. Fonts Manager | Custom Fonts plugin for WordPress
• All versions through and including 1.2 (fonts-manager-custom-fonts <= 1.2)
• WordPress installations with the plugin enabled

Discovery Timeline

• 2025-04-01 - CVE-2025-31578 published to NVD
• 2026-04-23 - Last updated in NVD database

Technical Details for CVE-2025-31578

Vulnerability Analysis

The vulnerability is a reflected XSS flaw classified under [CWE-79] (Improper Neutralization of Input During Web Page Generation). The plugin processes HTTP request parameters and reflects them into rendered HTML output without applying adequate sanitization or context-aware output encoding. An attacker can construct a crafted URL containing JavaScript payloads in vulnerable parameters and deliver it through phishing, malicious links, or third-party sites.

When a logged-in WordPress user, particularly an administrator, follows the link, the injected payload executes in the browser under the origin of the WordPress site. The scope change in the CVSS vector reflects that an attack against the plugin can affect the broader WordPress application, including session cookies and admin functionality.

Root Cause

The root cause is missing input neutralization in the fonts-manager-custom-fonts plugin. Request parameters are inserted into HTML responses without functions such as esc_html(), esc_attr(), or wp_kses() being applied. WordPress provides these helpers specifically to prevent reflected XSS, but they are not used on the affected code paths in versions up to 1.2.

Attack Vector

Exploitation is network-based and requires user interaction. The attacker delivers a malicious URL that includes a JavaScript payload in a vulnerable parameter handled by the plugin. When the victim loads the URL, the server reflects the unsanitized input into the response, and the browser executes the script. The vulnerability mechanism follows the standard reflected XSS pattern documented in the Patchstack WordPress Vulnerability Report. No verified public proof-of-concept code is available at this time.

Detection Methods for CVE-2025-31578

Indicators of Compromise

• HTTP requests to WordPress endpoints associated with the fonts-manager-custom-fonts plugin containing URL-encoded <script>, onerror=, onload=, or javascript: strings in query parameters.
• Unexpected outbound requests from administrator browsers to attacker-controlled domains shortly after clicking external links.
• New or modified WordPress administrator accounts, plugin installations, or theme edits that correlate with admin browser activity following suspicious link clicks.

Detection Strategies

• Review WordPress and reverse proxy access logs for request parameters containing common XSS payload markers targeting plugin paths.
• Deploy a Web Application Firewall (WAF) with rules that match reflected XSS patterns in query strings and POST bodies.
• Correlate browser telemetry from administrator endpoints with WordPress audit logs to identify script execution following malicious link delivery.

Monitoring Recommendations

• Enable WordPress audit logging for plugin, theme, and user account changes and forward events to a centralized SIEM.
• Monitor referrer headers and unusual GET parameter lengths on plugin-related URLs.
• Alert on installations of fonts-manager-custom-fonts at version 1.2 or earlier across managed WordPress estates.

How to Mitigate CVE-2025-31578

Immediate Actions Required

• Identify all WordPress sites running fonts-manager-custom-fonts version 1.2 or earlier and prioritize them for remediation.
• Update the plugin to a patched version as soon as the vendor releases one, or deactivate and remove the plugin if no fix is available.
• Force a password reset and invalidate active sessions for WordPress administrators on affected sites.

Patch Information

At the time of NVD publication, the advisory lists affected versions through 1.2 with no fixed version specified. Consult the Patchstack WordPress Vulnerability Report for the current patch status and vendor updates.

Workarounds

• Deactivate and uninstall the fonts-manager-custom-fonts plugin until a fixed version is published.
• Deploy WAF rules that block reflected XSS payloads targeting plugin endpoints and enforce strict input validation at the perimeter.
• Apply a strong Content Security Policy (CSP) that restricts inline scripts and limits script sources to trusted origins.
• Restrict administrative access to trusted IP ranges and require multi-factor authentication for WordPress administrators.

# Example WAF rule (ModSecurity) to block common reflected XSS payloads
SecRule ARGS "@rx (?i)(<script|onerror=|onload=|javascript:)" \
  "id:1003158,phase:2,deny,status:403,msg:'Reflected XSS attempt against WordPress plugin'"

# Example CSP header for WordPress (adjust sources to your environment)
Header set Content-Security-Policy "default-src 'self'; script-src 'self'; object-src 'none'; base-uri 'self'"