CVE-2026-27056: iThemes Sync Auth Bypass Vulnerability

CVE-2026-27056 Overview

CVE-2026-27056 is a Missing Authorization vulnerability [CWE-862] affecting the StellarWP iThemes Sync WordPress plugin (ithemes-sync). The flaw exists in versions up to and including 3.2.8 and stems from incorrectly configured access control security levels. Authenticated users with low privileges can invoke plugin functionality that should be restricted to higher-privileged roles. The vulnerability impacts integrity but does not directly expose confidential data or affect availability. Exploitation requires network access to a vulnerable WordPress installation and valid low-privileged credentials.

Critical Impact
Low-privileged authenticated users can bypass access control checks in iThemes Sync and exploit functionality intended for administrators, leading to limited integrity impact on the WordPress site.

Affected Products

StellarWP iThemes Sync (ithemes-sync) plugin for WordPress
All versions from initial release through 3.2.8
WordPress sites with the iThemes Sync plugin installed and activated

Discovery Timeline

2026-02-19 - CVE-2026-27056 published to NVD
2026-04-28 - Last updated in NVD database

Technical Details for CVE-2026-27056

Vulnerability Analysis

The vulnerability is a broken access control issue in the iThemes Sync plugin, which provides remote management capabilities for WordPress sites. The plugin exposes endpoints intended for site administrators but fails to enforce proper authorization checks on those endpoints. An attacker holding a low-privileged account on the target WordPress site can issue requests to these endpoints and trigger functionality reserved for privileged roles. The defect is classified under CWE-862: Missing Authorization, indicating the application performs no authorization check before executing sensitive actions. The EPSS data indicates a low probability of exploitation in the near term, but the issue remains relevant for any site exposing iThemes Sync to authenticated users.

Root Cause

The root cause is incorrectly configured access control security levels within plugin request handlers. The handlers either omit a capability check (for example, current_user_can()) or rely on insufficient role validation before performing privileged operations. As a result, the plugin treats authenticated requests as authorized regardless of the requesting user's role.

Attack Vector

The attack is network-based and requires low privileges with no user interaction. An attacker authenticates to the WordPress instance using any account that permits login, then issues crafted HTTP requests to vulnerable iThemes Sync endpoints. Successful requests execute privileged actions, producing a limited integrity impact on the site configuration or managed assets. Confidentiality and availability remain unaffected per the published metrics.

No verified public proof-of-concept code is available. Refer to the Patchstack advisory for technical context on the affected endpoints.

Detection Methods for CVE-2026-27056

Indicators of Compromise

Unexpected HTTP requests to iThemes Sync plugin endpoints originating from accounts with subscriber or contributor-level roles.
Modifications to WordPress site configuration or managed asset state without a corresponding administrator action in audit logs.
Authentication events for low-privileged accounts followed immediately by plugin API calls.

Detection Strategies

Review WordPress access logs for requests to ithemes-sync plugin paths and correlate the requesting user role against the action performed.
Enable WordPress audit logging plugins to capture privileged operations and flag operations executed by non-administrator accounts.
Compare installed plugin versions against 3.2.8 and lower across the WordPress estate to identify exposed instances.

Monitoring Recommendations

Forward web server and WordPress application logs to a centralized SIEM for role-versus-action correlation.
Alert on bursts of HTTP requests to iThemes Sync endpoints from a single authenticated session.
Track plugin version inventory and trigger alerts when sites remain on vulnerable releases after a patch is published.

How to Mitigate CVE-2026-27056

Immediate Actions Required

Identify all WordPress sites running iThemes Sync 3.2.8 or earlier and prioritize them for remediation.
Update the plugin to a fixed version once the vendor publishes a release addressing the access control flaw.
Audit existing low-privileged WordPress accounts and remove unused or unnecessary accounts to reduce the attack surface.
Review recent plugin activity logs for signs of unauthorized actions performed by non-administrator accounts.

Patch Information

The vulnerability affects iThemes Sync versions up to and including 3.2.8. Consult the Patchstack advisory for iThemes Sync for the latest fixed version and patch status. Apply the vendor-supplied update through the WordPress plugin manager or via WP-CLI.

Workarounds

Temporarily deactivate the iThemes Sync plugin on affected sites until a patched version is installed.
Restrict access to the WordPress administrative interface and plugin endpoints using IP allowlisting at the web server or web application firewall layer.
Enforce strong authentication and reduce the number of accounts with login privileges to the WordPress instance.

bash

# Inventory and disable iThemes Sync via WP-CLI on affected sites
wp plugin list --name=ithemes-sync --fields=name,status,version
wp plugin deactivate ithemes-sync