CVE-2026-42668 Overview
CVE-2026-42668 is a broken authentication vulnerability in the Email Marketing for WooCommerce by Omnisend plugin for WordPress. The flaw affects all versions up to and including 1.18.0. Unauthenticated attackers can exploit the issue over the network without user interaction. The vulnerability is classified under CWE-288: Authentication Bypass Using an Alternate Path or Channel.
Successful exploitation results in confidentiality impact, enabling adversaries to access protected functionality or data exposed by the plugin. The issue is tracked publicly via the Patchstack Vulnerability Report.
Critical Impact
Unauthenticated attackers can bypass authentication controls in the Omnisend plugin remotely, leading to exposure of sensitive marketing and customer data on WooCommerce stores.
Affected Products
- Email Marketing for WooCommerce by Omnisend plugin for WordPress
- All versions up to and including 1.18.0
- WooCommerce-enabled WordPress sites with the omnisend-connect plugin installed
Discovery Timeline
- 2026-06-15 - CVE-2026-42668 published to the National Vulnerability Database (NVD)
- 2026-06-17 - Last updated in NVD database
Technical Details for CVE-2026-42668
Vulnerability Analysis
The vulnerability is a broken authentication weakness in the Omnisend WooCommerce email marketing plugin. The plugin exposes functionality reachable without valid authentication credentials. Attackers reach the vulnerable code path over the network with low attack complexity and no required privileges or user interaction.
The weakness maps to [CWE-288], which covers cases where an alternate path or channel bypasses the standard authentication mechanism. Exploitation impacts confidentiality of plugin-managed data without modifying integrity or availability. The current EPSS probability is 0.528%, placing the vulnerability at the 40.4 percentile of likelihood of exploitation activity.
Root Cause
The root cause is missing or improperly enforced authentication checks on one or more plugin endpoints in versions through 1.18.0. The plugin trusts requests on a code path that should require an authenticated WordPress session or valid API credential. Patchstack categorizes the issue as unauthenticated broken authentication, indicating the access control logic fails before reaching the protected resource.
Attack Vector
The attack vector is network-based against any WordPress site running a vulnerable version of omnisend-connect. An attacker sends crafted HTTP requests directly to the exposed plugin endpoint. No prior authentication, social engineering, or user interaction is required. Public technical details for the specific endpoint and request structure are limited to the Patchstack Vulnerability Report at this time.
Detection Methods for CVE-2026-42668
Indicators of Compromise
- Unauthenticated HTTP requests to omnisend-connect plugin endpoints under /wp-content/plugins/omnisend-connect/ or related REST routes
- Unexpected outbound data flows from the WordPress host to unknown destinations following plugin endpoint access
- WordPress access logs showing repeated requests from a single source IP to Omnisend plugin paths without prior authentication cookies
Detection Strategies
- Inventory all WordPress installations and identify sites running omnisend-connect version 1.18.0 or earlier
- Review web server access logs for anomalous request patterns targeting Omnisend plugin URLs
- Deploy web application firewall (WAF) rules to flag unauthenticated access attempts to plugin REST endpoints
Monitoring Recommendations
- Forward WordPress and web server logs to a centralized log analytics platform for correlation
- Alert on spikes in 200-status responses to plugin endpoints originating from unauthenticated sessions
- Track plugin version metadata across managed WordPress sites to detect unpatched installations
How to Mitigate CVE-2026-42668
Immediate Actions Required
- Identify all WordPress sites running omnisend-connect version 1.18.0 or earlier and prioritize them for update
- Apply the vendor-supplied plugin update as soon as a fixed version is published on the WordPress plugin repository
- Restrict access to /wp-admin and plugin REST endpoints using IP allowlists or upstream WAF rules until patching is complete
Patch Information
Refer to the Patchstack Vulnerability Report for the latest fixed version information from Omnisend. Update the plugin to a version higher than 1.18.0 once available. Verify the installed version in the WordPress admin Plugins page after the update.
Workarounds
- Temporarily deactivate the Email Marketing for WooCommerce by Omnisend plugin until a patched version is applied
- Place the WordPress site behind a WAF with virtual patching rules targeting unauthenticated requests to Omnisend plugin endpoints
- Rotate any API keys, tokens, or integration secrets configured within the Omnisend plugin after patching
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
