CVE-2026-16948: Solace Extra Plugin Privilege Escalation

CVE-2026-16948 Overview

CVE-2026-16948 is a broken access control vulnerability [CWE-284] in the Solace Extra WordPress plugin versions prior to 1.6.1. The plugin registers several AJAX actions without capability checks and exposes the protecting nonce on admin pages that low-privileged users can reach. Authenticated attackers with a role as low as Subscriber can invoke these actions to modify site-wide presentation settings and delete imported site-builder content. The flaw affects site integrity and availability without requiring elevated privileges or user interaction.

Critical Impact
A Subscriber-level account can alter global site appearance and destroy imported site-builder content, causing integrity and availability damage on affected WordPress sites.

Affected Products

Solace Extra WordPress plugin versions prior to 1.6.1
WordPress sites that allow Subscriber-level registration with the plugin installed
Any WordPress deployment using vulnerable Solace Extra AJAX endpoints

Discovery Timeline

2026-08-08 - CVE-2026-16948 published to NVD
2026-08-11 - Last updated in NVD database

Technical Details for CVE-2026-16948

Vulnerability Analysis

The Solace Extra plugin registers multiple AJAX actions through the WordPress wp_ajax_ hook family. These handlers omit capability checks such as current_user_can(), so any authenticated user can call them. The plugin also renders its protecting nonce on admin screens accessible to low-privileged roles, defeating the intended CSRF-style access barrier.

A Subscriber can read the nonce from a reachable admin page, then issue authenticated AJAX requests to modify global presentation settings or delete imported site-builder content. The vulnerability produces high integrity and availability impact while leaving confidentiality unaffected.

Root Cause

The root cause is missing authorization enforcement in AJAX action handlers combined with improper nonce scoping. Capability checks are absent from privileged handlers, and the nonce that guards those handlers is exposed to any authenticated user who can load the relevant admin page. Nonces provide request authenticity, not authorization, so their exposure to Subscribers eliminates the only remaining barrier.

Attack Vector

An attacker registers or compromises a Subscriber account on a target site. The attacker loads an admin page reachable at that privilege level and extracts the exposed nonce from the rendered HTML. The attacker then sends POST requests to admin-ajax.php containing the vulnerable action name and the harvested nonce, triggering settings modification or deletion of imported site-builder content.

See the WPScan Vulnerability Report for detailed handler names and affected endpoints.

Detection Methods for CVE-2026-16948

Indicators of Compromise

Unexpected POST requests from low-privileged user sessions to /wp-admin/admin-ajax.php referencing Solace Extra action names
Unauthorized changes to site-wide theme, layout, or presentation options in the WordPress options table
Missing or deleted imported site-builder templates and demo content records
Subscriber accounts generating administrative-style AJAX traffic

Detection Strategies

Correlate admin-ajax.php requests with the authenticated user role and flag Subscriber-role calls to plugin-specific actions
Audit wp_options changes for unexpected modifications to Solace Extra settings keys
Review WordPress activity logs for content deletions performed by non-Editor accounts

Monitoring Recommendations

Enable request logging on admin-ajax.php and retain user role context per request
Alert on new Subscriber registrations followed by AJAX activity within a short window
Monitor plugin option and post table changes with database-level auditing

How to Mitigate CVE-2026-16948

Immediate Actions Required

Update the Solace Extra plugin to version 1.6.1 or later on all WordPress instances
Disable open user registration or restrict the default role to a non-Subscriber value until patched
Review Subscriber accounts for anomalous creation dates and remove untrusted accounts
Restore modified presentation settings and any deleted site-builder content from backups

Patch Information

Upgrade to Solace Extra version 1.6.1 or later. The vendor release adds capability checks to the affected AJAX handlers and restricts nonce exposure. Reference the WPScan Vulnerability Report for version details.

Workarounds

Deactivate the Solace Extra plugin until the patched version is installed
Block unauthenticated and Subscriber-role access to admin-ajax.php actions associated with the plugin using a web application firewall rule
Set the WordPress users_can_register option to false to prevent new low-privileged account creation

bash

# Disable open registration via WP-CLI as a temporary workaround
wp option update users_can_register 0

# Deactivate the vulnerable plugin until patched
wp plugin deactivate solace-extra

# After patching, update and reactivate
wp plugin update solace-extra --version=1.6.1
wp plugin activate solace-extra