CVE-2025-39372: WordPress Events Calendar Reflected XSS Flaw

CVE-2025-39372 Overview

CVE-2025-39372 is a reflected cross-site scripting (XSS) vulnerability in the elbisnero WordPress Events Calendar Registration & Tickets plugin (wpeventplus). The flaw affects all plugin versions up to and including 2.6.0. The vulnerability stems from improper neutralization of user-supplied input during web page generation, classified as [CWE-79]. Attackers can craft malicious URLs that execute arbitrary JavaScript in a victim's browser session when clicked. Successful exploitation requires user interaction but no authentication, and the scope change indicator means impact extends beyond the vulnerable component.

Critical Impact

Attackers can hijack user sessions, steal authentication cookies, perform actions on behalf of authenticated WordPress administrators, and deliver phishing content from a trusted domain.

Affected Products

• WordPress Events Calendar Registration & Tickets plugin (wpeventplus) versions up to and including 2.6.0
• WordPress sites running the elbisnero wpeventplus plugin
• Any WordPress installation with the vulnerable plugin active

Discovery Timeline

• 2025-05-19 - CVE-2025-39372 published to NVD
• 2026-04-23 - Last updated in NVD database

Technical Details for CVE-2025-39372

Vulnerability Analysis

The vulnerability is a reflected XSS flaw in the wpeventplus plugin. User-controlled input is reflected back into HTTP responses without proper output encoding or input sanitization. When a victim clicks a malicious link, the injected script executes in the context of the victim's browser session on the trusted WordPress domain.

The Exploit Prediction Scoring System (EPSS) score is 0.185%, placing this CVE in the 39th percentile for exploitation likelihood. While not widely exploited at scale, reflected XSS vulnerabilities in WordPress plugins remain common targets in phishing-driven campaigns.

Root Cause

The root cause is missing or insufficient input neutralization in the plugin code paths that handle request parameters. Input values passed via HTTP GET or POST requests are echoed into HTML output without escaping characters such as <, >, ", and '. This allows arbitrary HTML and JavaScript markup to be injected into rendered pages.

Attack Vector

The attack vector is network-based and requires user interaction. An attacker crafts a URL containing malicious JavaScript payloads in vulnerable query parameters. The attacker then delivers the URL through phishing emails, social media posts, or compromised third-party sites. When a logged-in WordPress user visits the link, the payload executes with the privileges of that user session.

Because the scope is changed, the injected script can access resources beyond the vulnerable plugin context, including administrative cookies and session tokens. Technical details and proof-of-concept information are available in the Patchstack XSS Vulnerability Report.

Detection Methods for CVE-2025-39372

Indicators of Compromise

• Suspicious URL parameters containing HTML tags such as <script>, <img>, or <svg> directed at wpeventplus plugin endpoints
• Unexpected outbound requests from WordPress administrator browsers to attacker-controlled domains
• Unauthorized changes to WordPress administrator accounts or new admin users created without explanation
• Web server access logs showing encoded JavaScript payloads (%3Cscript%3E, javascript:) in query strings targeting the plugin

Detection Strategies

• Inspect web server access logs for requests to wpeventplus plugin URLs containing reflected input patterns and encoded script tags
• Deploy a web application firewall (WAF) with rules tuned to detect reflected XSS patterns against WordPress plugin endpoints
• Monitor browser Content Security Policy (CSP) violation reports for inline script execution on plugin-served pages
• Use vulnerability scanners that track WordPress plugin versions to flag installations of wpeventplus at or below version 2.6.0

Monitoring Recommendations

• Audit WordPress administrator session activity for anomalous actions following clicks on external links
• Alert on creation of new WordPress administrator accounts or changes to user roles
• Track plugin version inventory across all managed WordPress instances and flag outdated installations
• Forward WordPress and web server logs to a centralized SIEM for correlation against phishing campaign indicators

How to Mitigate CVE-2025-39372

Immediate Actions Required

• Update the WordPress Events Calendar Registration & Tickets plugin to a version above 2.6.0 once a patched release is available
• Disable or remove the wpeventplus plugin from production WordPress installations until a patch is verified
• Force password resets and session invalidation for WordPress administrators if exploitation is suspected
• Review web server logs for evidence of malicious URLs targeting the plugin and identify affected user accounts

Patch Information

At the time of publication, the vulnerability affects all versions of wpeventplus up to and including 2.6.0. Administrators should monitor the plugin's official WordPress repository page and the Patchstack advisory for patched release availability and apply updates immediately upon release.

Workarounds

• Deploy a WAF rule blocking requests containing script tags, javascript: URIs, or encoded XSS payloads in wpeventplus plugin URLs
• Implement a strict Content Security Policy (CSP) header that disallows inline JavaScript execution on WordPress pages
• Restrict access to WordPress administrative functions by IP allowlist where operationally feasible
• Train WordPress administrators to avoid clicking unsolicited links pointing to their own WordPress sites with unusual query parameters

# Example WAF rule (ModSecurity) to block reflected XSS payloads on wpeventplus URLs
SecRule REQUEST_URI "@contains wpeventplus" \
    "chain,phase:2,deny,status:403,id:1039372,msg:'Blocked potential XSS on wpeventplus (CVE-2025-39372)'"
SecRule ARGS "@rx (?i)(<script|javascript:|onerror=|onload=|<svg|<img[^>]+src)" \
    "t:none,t:urlDecodeUni"