CVE-2026-11603: Elementor Product Filter Widget XSS Flaw

CVE-2026-11603 Overview

CVE-2026-11603 is a Reflected Cross-Site Scripting (XSS) vulnerability in the Product Filter Widget for Elementor plugin for WordPress. All versions up to and including 1.0.6 are affected. The flaw resides in the args[filterFormArray] parameter, which the plugin processes without sufficient input sanitization or output escaping. The vulnerable AJAX endpoint is registered via wp_ajax_nopriv_ with no nonce verification or capability check, allowing unauthenticated attackers to inject arbitrary web scripts. Exploitation requires tricking a victim into clicking an attacker-controlled link or visiting a page that auto-submits a CSRF-style form to admin-ajax.php.

Critical Impact
Unauthenticated attackers can execute arbitrary JavaScript in a victim's browser session, enabling session theft, account takeover, and redirection to malicious resources.

Affected Products

Product Filter Widget for Elementor plugin for WordPress
All versions up to and including 1.0.6
WordPress sites using the vulnerable plugin with the Eszpf_Ajax_Handler controller

Discovery Timeline

2026-06-09 - CVE-2026-11603 published to NVD
2026-06-09 - Last updated in NVD database

Technical Details for CVE-2026-11603

Vulnerability Analysis

The vulnerability is classified as [CWE-79] Improper Neutralization of Input During Web Page Generation. The Product Filter Widget for Elementor plugin exposes an AJAX handler in inc/controller/Eszpf_Ajax_Handler.php that accepts user-supplied data through the args[filterFormArray] parameter. The handler reflects this input back into the HTTP response without applying sanitization functions such as sanitize_text_field() or output escaping helpers such as esc_html() or esc_attr().

Because the endpoint is bound through wp_ajax_nopriv_, it is reachable by unauthenticated clients. The plugin omits nonce verification through check_ajax_referer() and performs no capability checks, removing standard WordPress request-origin controls.

Root Cause

The root cause is the combination of three coding defects: missing input sanitization on the args[filterFormArray] parameter, missing output escaping when the data is rendered into the response, and absent CSRF protections on the public AJAX endpoint. Each defect on its own would limit the attack surface, but together they allow attacker-controlled payloads to flow directly into the response body.

Attack Vector

An attacker hosts a malicious page that contains an auto-submitting HTML form targeting the victim site's admin-ajax.php endpoint. When the victim visits the page, the form posts a crafted args[filterFormArray] value containing JavaScript. The vulnerable server reflects the payload, and the script executes in the victim's browser within the context of the WordPress site. Successful exploitation can lead to cookie theft, session hijacking, defacement, or pivoting to authenticated administrative actions if the victim is a privileged user.

No verified public exploit code is available. See the WordPress Plugin Code Review and the Wordfence Vulnerability Report for technical details.

Detection Methods for CVE-2026-11603

Indicators of Compromise

POST requests to /wp-admin/admin-ajax.php containing the args[filterFormArray] parameter with HTML or JavaScript syntax such as <script>, onerror=, or javascript:.
Referer headers on admin-ajax.php requests pointing to external or unexpected domains, indicating CSRF-style delivery.
Browser console errors or Content Security Policy (CSP) violations on pages rendered after a filter request.

Detection Strategies

Inspect web server access logs for action= parameters tied to the Product Filter Widget AJAX handler combined with encoded angle brackets or event-handler attributes in filterFormArray.
Deploy WAF rules that flag reflected XSS patterns in POST bodies destined for admin-ajax.php.
Correlate unauthenticated admin-ajax.php traffic volume against baseline to surface CSRF-driven exploitation attempts.

Monitoring Recommendations

Enable verbose logging on the WordPress reverse proxy or WAF for all admin-ajax.php POST bodies.
Track outbound requests from administrator browsers to unusual domains immediately following filter widget interactions.
Alert on new WordPress administrator account creation or role changes within a short window after suspicious AJAX traffic.

How to Mitigate CVE-2026-11603

Immediate Actions Required

Update the Product Filter Widget for Elementor plugin to a version newer than 1.0.6 once the vendor publishes a patched release.
Disable or remove the plugin if a fixed version is not yet available and the widget is non-essential.
Review WordPress administrator accounts for unauthorized changes and rotate session cookies for privileged users.

Patch Information

At the time of publication, no fixed version has been documented in the NVD entry. Site operators should monitor the Wordfence Vulnerability Report and the plugin's repository for an updated release that introduces sanitization, output escaping, and nonce verification on the Eszpf_Ajax_Handler endpoint.

Workarounds

Block or rate-limit unauthenticated POST requests to admin-ajax.php that include the filterFormArray parameter at the WAF or reverse proxy layer.
Enforce a strict Content Security Policy that disallows inline scripts to reduce the impact of reflected payloads.
Require administrators to use isolated browser profiles when managing WordPress to limit cross-site request exposure.

bash

# Example WAF rule (ModSecurity) blocking suspicious filterFormArray payloads
SecRule ARGS_NAMES "@rx filterFormArray" \
    "id:1026116030,phase:2,deny,status:403,\
    msg:'CVE-2026-11603 Reflected XSS attempt blocked',\
    chain"
    SecRule ARGS "@rx (?i)(<script|onerror=|javascript:|onload=)" \
        "t:none,t:urlDecodeUni"