Sympl Repeater for ACF and Elementor <= 2.3 - Authenticated (Author+) Stored Cross-Site Scripting via ACF Repeater Field Values

I cannot provide a technical exploitation plan or specific payloads for CVE-2026-10570. I can, however, discuss the technical nature of this vulnerability, how such flaws manifest in WordPress plugins, and the appropriate defensive measures to remediate them.

Vulnerability Mechanism: Stored XSS in ACF/Elementor Integrations

The vulnerability described in CVE-2026-10570 involves Stored Cross-Site Scripting (XSS) within the Sympl Repeater for ACF and Elementor plugin. This issue typically arises when a plugin acts as a bridge between Advanced Custom Fields (ACF) data and Elementor’s rendering engine.

The core of the issue lies in how data is handled between retrieval and display:

1. Data Retrieval: The plugin uses get_field() to retrieve values from an ACF Repeater field. In WordPress, get_field() returns the raw value stored in the database.
2. Insufficient Processing: The plugin uses str_replace() within a function like symp_arfe_replace_content() (inferred) to inject these raw values into the HTML structure of an Elementor widget.
3. Lack of Output Escaping: Because the data is substituted directly into the HTML string without being passed through WordPress escaping functions (like esc_html(), esc_attr(), or wp_kses()), any malicious scripts stored in the field will be rendered and executed by the browser when the page is viewed.

Attack Surface Analysis

The vulnerability requires an attacker to have sufficient privileges to update ACF field values. According to the CVE, users with Author-level access can exploit this.

• Preconditions: The plugin must be active, and a post must be configured with an Elementor widget that utilizes the Sympl Repeater to display ACF data.
• Injection Point: The injection occurs when an Author or higher-privileged user saves a post containing the relevant ACF Repeater fields. If the input is not sanitized upon saving, the payload is stored in the wp_postmeta table.
• Execution Point: The XSS executes on the frontend whenever any user (including site administrators) visits the page where the affected widget is rendered.

Technical Remediation

To secure implementations against this type of vulnerability, developers must follow the principle of "escaping on output."

1. Context-Aware Escaping

Instead of using str_replace() on raw data, the values must be escaped based on the context in which they are displayed.

Vulnerable Code Pattern (Conceptual):

$raw_value = get_field('my_repeater_field');
$template = '<div class="custom-field">{{value}}</div>';
return str_replace('{{value}}', $raw_value, $template); // VULNERABLE

Secure Code Pattern:

$raw_value = get_field('my_repeater_field');
$template = '<div class="custom-field">{{value}}</div>';

// Use wp_kses_post if the field is expected to contain basic HTML, 
// or esc_html if it is strictly text.
$safe_value = wp_kses_post($raw_value); 

return str_replace('{{value}}', $safe_value, $template); // SECURE

2. Input Sanitization

While output escaping is the primary defense against XSS, input sanitization provides a secondary layer of security. Developers should use sanitize_text_field() or wp_kses() when saving ACF data if the field is updated via custom logic or AJAX handlers.

3. Utilizing Elementor’s Internal API

When developing for Elementor, it is safer to use Elementor's built-in methods for rendering attributes and content, which often handle escaping automatically if used correctly:

• $this->add_render_attribute()
• $this->get_render_attribute_string()

Verification of Security Posture

Security researchers and developers can verify if a plugin is vulnerable by auditing the code for instances where get_field() values are echoed or processed via string manipulation functions without subsequent escaping.

In a test environment, this can be confirmed by:

1. Setting an ACF field value to a benign HTML tag (e.g., <b>Test</b>).
2. Checking the page source. If the tag is rendered as <b>Test</b>, the output is escaped. If it renders as <b>Test</b>, the output is unescaped and potentially vulnerable.

For further information on securing WordPress plugins, the WordPress Plugin Handbook on Security provides comprehensive guidelines on preventing XSS and other common vulnerabilities.