CVE-2026-17553: WP EasyCart Privilege Escalation Vulnerability

CVE-2026-17553 Overview

CVE-2026-17553 is a privilege escalation vulnerability in the WP EasyCart plugin for WordPress affecting all versions up to and including 5.9.3. The flaw resides in the ec_ajax_save_page_default_options() AJAX handler, which iterates over every $_POST key and passes it directly into update_option() without an allowlist. The handler is gated on either manage_options or the plugin's custom wpec_manager capability. Because the built-in wpec_store_manager role holds wpec_manager but not manage_options, authenticated attackers with Store Manager-level access can overwrite arbitrary WordPress options and elevate themselves to administrator [CWE-269].

Critical Impact
Store Manager accounts can promote themselves to administrator, gaining full control of the WordPress site, its data, and its underlying hosting environment.

Affected Products

WP EasyCart plugin for WordPress, versions up to and including 5.9.3
WordPress installations using the built-in wpec_store_manager role
Sites exposing frontend product or category templates that render the required nonce

Discovery Timeline

2026-09-09 - CVE-2026-17553 published to the National Vulnerability Database (NVD)
2026-09-09 - Last updated in NVD database

Technical Details for CVE-2026-17553

Vulnerability Analysis

The vulnerability is a broken access control and privilege escalation flaw in the WP EasyCart plugin. The ec_ajax_save_page_default_options() handler is designed to save plugin page defaults but accepts arbitrary option names from user-supplied input. Rather than restricting writes to a fixed set of plugin-owned options, the handler loops through every submitted POST parameter and passes the key and value into WordPress core's update_option() function.

The capability check compounds the flaw. The handler accepts requests from users holding either manage_options (administrators) or wpec_manager. The plugin assigns wpec_manager to its custom wpec_store_manager role, which is not intended to modify site-wide WordPress settings. Any user in that role can rewrite security-critical WordPress options.

Root Cause

The root cause is missing allowlist validation combined with an overly permissive capability gate. Options such as default_role and users_can_register are treated as writable by a role that should be limited to storefront management tasks. The required AJAX nonce is emitted on frontend product and category templates that render for any user holding wpec_manager, so nonce validation does not act as an effective secondary control.

Attack Vector

An attacker authenticated as a Store Manager retrieves the nonce from a public-facing product or category page. The attacker then submits a POST request to the vulnerable AJAX handler containing default_role=administrator and users_can_register=1. With registration enabled and the default role set to administrator, the attacker uses the standard WordPress registration flow (wp-login.php?action=register) to create a new account. The new account is automatically assigned the administrator role, granting full site control.

Full technical details are documented in the Wordfence Vulnerability Report and the affected source in the WordPress EasyCart Admin Code.

Detection Methods for CVE-2026-17553

Indicators of Compromise

WordPress options default_role set to administrator or users_can_register set to 1 when not expected by site policy.
New administrator accounts created shortly after AJAX POST requests to admin-ajax.php with the ec_ajax_save_page_default_options action.
Unexpected changes to wp_options timestamps attributable to accounts holding the wpec_store_manager role.

Detection Strategies

Review WordPress audit logs for calls to update_option() targeting core security options by non-administrator users.
Correlate admin-ajax.php requests containing the vulnerable action name with subsequent user registrations.
Enumerate active WordPress users and flag any administrator accounts created after Store Manager activity.

Monitoring Recommendations

Enable a WordPress activity log plugin that records option changes, role assignments, and user registrations.
Forward web server access logs and WordPress audit events into a centralized SIEM for behavioral analysis.
Alert on any modification of default_role, users_can_register, siteurl, or home outside a change window.

How to Mitigate CVE-2026-17553

Immediate Actions Required

Update the WP EasyCart plugin to a version later than 5.9.3 that includes the fix referenced in the WordPress EasyCart Changeset Update.
Audit all accounts holding the wpec_store_manager role and revoke access from any that are unnecessary.
Review the default_role and users_can_register options and reset them to safe values if tampered with.
Enumerate administrator accounts and remove any that cannot be attributed to a legitimate administrator.

Patch Information

The vendor addressed the vulnerability in a release following 5.9.3. Site owners should apply the plugin update through the WordPress dashboard or by deploying the fixed release from the WordPress plugin repository. Confirm the installed version reports higher than 5.9.3 after the update completes.

Workarounds

Deactivate the WP EasyCart plugin until the patched version can be installed.
Remove the wpec_manager capability from the wpec_store_manager role using a custom mu-plugin until patched.
Use a web application firewall rule to block POST requests to admin-ajax.php where the action parameter equals ec_ajax_save_page_default_options and the payload contains default_role or users_can_register.

bash

# Example: remove the wpec_manager capability from the Store Manager role via WP-CLI
wp cap remove wpec_store_manager wpec_manager

# Verify sensitive options remain at safe values
wp option get default_role
wp option get users_can_register