CVE-2021-47922: Slider by Soliloquy XSS Vulnerability

CVE-2021-47922 Overview

CVE-2021-47922 is a stored cross-site scripting (XSS) vulnerability [CWE-79] affecting the Slider by Soliloquy WordPress plugin version 2.6.2. The flaw allows authenticated attackers to inject malicious JavaScript through the slider title parameter. The injected payload persists in the database and executes whenever a user views the slider on either administrative or public-facing pages. Successful exploitation can lead to session hijacking, privilege abuse, and redirection of site visitors.

Critical Impact

Authenticated attackers can store JavaScript that executes in administrator browsers, enabling account takeover and pivot to full WordPress site compromise.

Affected Products

• Slider by Soliloquy WordPress plugin version 2.6.2
• Soliloquy Lite WordPress plugin (related distribution)
• WordPress installations using the affected plugin version

Discovery Timeline

• 2026-05-10 - CVE-2021-47922 published to NVD
• 2026-05-12 - Last updated in NVD database

Technical Details for CVE-2021-47922

Vulnerability Analysis

The vulnerability resides in the slider creation and editing workflow of Slider by Soliloquy 2.6.2. The plugin accepts user-supplied input for the slider title field without enforcing sufficient output encoding or input sanitization. An authenticated user with permission to create or edit sliders can supply JavaScript within the title parameter. The payload is stored in the WordPress database and rendered to all subsequent viewers.

When administrators visit the slider management page, the stored script executes in their browser context. The same payload executes for unauthenticated visitors who load a page embedding the affected slider. This dual-context execution expands the attack surface beyond the typical administrator-only stored XSS.

Root Cause

The root cause is improper neutralization of input during web page generation [CWE-79]. The plugin fails to apply WordPress sanitization helpers such as sanitize_text_field() on input and does not escape output using functions like esc_html() or esc_attr() when rendering the title in HTML contexts.

Attack Vector

The attack requires network access to the WordPress administrative interface and authenticated low-privilege access sufficient to create or edit sliders. User interaction is required: an administrator or site visitor must load a page containing the malicious slider title for the payload to fire. The exploitation flow involves logging into WordPress, navigating to the Soliloquy slider editor, injecting a script payload such as a standard <script> tag in the title input, saving the slider, and waiting for a privileged user to view it.

A public proof of concept is referenced in Exploit-DB #50563 and the VulnCheck Advisory on Soliloquy.

Detection Methods for CVE-2021-47922

Indicators of Compromise

• Slider records in the WordPress wp_posts table containing <script>, onerror=, onload=, or javascript: strings in the title field
• Unexpected outbound requests from administrator browsers to attacker-controlled domains after visiting the slider management page
• New administrator accounts or modified user roles created shortly after a slider edit event
• Anomalous POST requests to wp-admin/admin.php?page=soliloquy containing encoded script payloads

Detection Strategies

• Query the WordPress database for stored slider entries containing HTML event handlers or script tags in title fields
• Inspect web server access logs for POST requests to Soliloquy plugin endpoints with suspicious payloads in form parameters
• Deploy a web application firewall rule set that flags XSS patterns submitted through plugin administrative pages
• Audit plugin version inventory across WordPress installations to identify hosts running Soliloquy 2.6.2

Monitoring Recommendations

• Enable WordPress activity logging to capture slider create, update, and delete events with the originating user account
• Monitor browser-side Content Security Policy (CSP) violation reports for inline script execution on /wp-admin/ pages
• Alert on creation of administrator accounts within a short window after a slider edit by a lower-privileged user

How to Mitigate CVE-2021-47922

Immediate Actions Required

• Upgrade Slider by Soliloquy beyond version 2.6.2 to a release that sanitizes the title parameter
• Audit all existing sliders for malicious HTML or JavaScript stored in title and description fields
• Restrict slider creation and editing capabilities to fully trusted administrative users only
• Rotate WordPress administrator credentials and active session tokens if exploitation is suspected

Patch Information

Review the VulnCheck Advisory on Soliloquy and the official Soliloquy WP Homepage for the latest plugin release. Update through the WordPress plugin manager or by replacing the plugin directory with the fixed version. Confirm the installed version using wp plugin list via WP-CLI after upgrade.

Workarounds

• Deactivate the Slider by Soliloquy plugin until a patched version is installed
• Apply a web application firewall rule that blocks <script> and event-handler patterns submitted to Soliloquy admin endpoints
• Implement a strict Content Security Policy that disallows inline script execution on WordPress admin pages
• Manually sanitize existing slider titles by editing each entry and removing HTML markup

# Configuration example: identify affected plugin version and disable it via WP-CLI
wp plugin list --name=soliloquy-lite --fields=name,status,version
wp plugin deactivate soliloquy-lite
wp plugin update soliloquy-lite