CVE-2025-27319: User List Plugin Reflected XSS Vulnerability

CVE-2025-27319 Overview

CVE-2025-27319 is a reflected Cross-Site Scripting (XSS) vulnerability [CWE-79] in the ivan82 User List WordPress plugin. The flaw affects all versions of the plugin up to and including 1.5.1. Attackers can craft malicious URLs that, when clicked by an authenticated or unauthenticated victim, execute arbitrary JavaScript in the victim's browser session. The issue stems from improper neutralization of user-supplied input during web page generation. Successful exploitation can lead to session theft, credential harvesting, defacement, or redirection to attacker-controlled infrastructure.

Critical Impact
Reflected XSS in the User List plugin enables attackers to execute arbitrary JavaScript in a victim's browser, potentially compromising WordPress administrator sessions and site integrity.

Affected Products

ivan82 User List WordPress plugin, versions through 1.5.1
WordPress installations with the user-list plugin active
Sites exposing the plugin's vulnerable endpoints to untrusted users

Discovery Timeline

2025-04-17 - CVE-2025-27319 published to NVD
2026-04-23 - Last updated in NVD database

Technical Details for CVE-2025-27319

Vulnerability Analysis

The vulnerability is a reflected Cross-Site Scripting issue classified under [CWE-79]. The User List plugin accepts user-controlled input through a request parameter and reflects that input into the rendered HTML response without proper sanitization or output encoding. When a victim follows a crafted link containing a JavaScript payload, the browser parses the injected script in the context of the WordPress site origin.

Because the attack vector is network-based and requires user interaction, exploitation depends on social engineering, such as phishing messages or malicious links embedded in third-party sites. The scope is changed, meaning the injected script can affect resources beyond the vulnerable component, including the WordPress admin interface if an administrator clicks the link. The EPSS data places the probability of exploitation at 0.437%.

Root Cause

The root cause is the absence of context-aware output encoding when the plugin renders user-supplied parameters into HTML. WordPress provides helper functions such as esc_html(), esc_attr(), and esc_url() for safe output, but the vulnerable code paths in User List versions through 1.5.1 reflect input directly into the response stream. This allows HTML and <script> constructs to break out of their intended data context.

Attack Vector

An attacker constructs a URL targeting the vulnerable plugin endpoint with a JavaScript payload in a reflected parameter. The attacker delivers the link to a target through phishing, forum posts, or malicious advertisements. When the victim opens the link in an authenticated session, the payload executes with the privileges of the victim, including the ability to issue requests to administrative endpoints, exfiltrate cookies that lack HttpOnly, or modify the rendered page.

The vulnerability mechanism is described in the Patchstack Vulnerability Report. No public exploit code is available at this time.

Detection Methods for CVE-2025-27319

Indicators of Compromise

HTTP request logs containing URL parameters with <script>, javascript:, or HTML event handlers such as onerror= and onload= directed at user-list plugin endpoints
Unexpected outbound requests from administrator browsers to unknown domains shortly after visiting plugin pages
New or modified WordPress administrator accounts created without a corresponding legitimate login event

Detection Strategies

Inspect web server access logs for encoded payloads such as %3Cscript%3E or %3Cimg%20src%3D targeting the plugin's request parameters
Deploy a Web Application Firewall (WAF) rule set that flags reflected XSS patterns in query strings, particularly those routed to wp-content/plugins/user-list/
Correlate referrer headers with payload-bearing requests to identify phishing campaigns delivering crafted links

Monitoring Recommendations

Enable verbose logging on the WordPress site and forward logs to a centralized analytics platform for retention and search
Monitor for anomalous administrator session activity, including unexpected wp-admin actions following access to plugin pages
Track plugin version inventory across managed WordPress sites and alert when User List1.5.1 or earlier is detected

How to Mitigate CVE-2025-27319

Immediate Actions Required

Audit all WordPress installations for the presence of the ivan82 User List plugin and identify any running version 1.5.1 or earlier
Deactivate and remove the User List plugin until a patched release is available and validated
Apply WAF rules to block reflected XSS payloads targeting the plugin's request parameters
Reset administrator session cookies and rotate credentials if exploitation is suspected

Patch Information

At the time of publication, no vendor-supplied patched version is referenced in the available advisory. Administrators should monitor the Patchstack Vulnerability Report for updates and apply any vendor release that supersedes version 1.5.1.

Workarounds

Remove the plugin entirely if no patched version is available
Restrict access to WordPress administrative interfaces by IP allowlisting or VPN-only access
Configure a strict Content Security Policy (CSP) that disallows inline scripts and limits script sources to trusted origins
Set the HttpOnly and Secure flags on authentication cookies to reduce the impact of script execution

bash

# Example: Disable and remove the vulnerable plugin via WP-CLI
wp plugin deactivate user-list
wp plugin delete user-list

# Example: Apache mod_security rule snippet to block common XSS payloads
SecRule ARGS "@rx (?i)(<script|javascript:|onerror=|onload=)" \
    "id:1002701,phase:2,deny,status:403,msg:'Reflected XSS attempt blocked'"