CVE-2026-57632: Broken Access Control in Omnisend WooCommerce Email Plugin

Technical summary

CVE-2026-57632 is classified as a broken access control flaw (CWE-862) in the Omnisend Email Marketing for WooCommerce plugin. The vulnerability stems from insufficient permission validation when handling subscriber-related operations. The CVSS 3.1 score of 5.4 (MEDIUM) reflects a network-exploitable attack requiring low complexity and valid authentication credentials, with impacts limited to integrity and availability—no confidentiality breach occurs. The vulnerability does not appear on the CISA Known Exploited Vulnerabilities (KEV) catalog as of the current date.

Business impact

For WooCommerce site operators using Omnisend, this vulnerability could allow staff accounts or compromised user sessions to tamper with email subscriber lists, segmentation rules, or campaign settings without proper authorization. This may result in loss of subscriber data integrity, unwanted modifications to email campaigns, or reputational damage if subscriber information is altered maliciously. Organizations relying on accurate subscriber management for compliance (GDPR, CAN-SPAM) or marketing accuracy should prioritize remediation.

Affected systems

Email Marketing for WooCommerce by Omnisend version 1.19.0 and all prior versions are affected. Organizations running unpatched installations of this plugin on WooCommerce-based e-commerce platforms are at risk. The vulnerability does not affect other versions, products, or platforms outside of this specific plugin.

Exploitability

Exploitation requires valid WordPress login credentials—an attacker cannot exploit this flaw remotely without authentication. However, the low complexity attack vector and absence of additional user interaction steps mean that once an authenticated user gains access, they can readily exploit the broken access controls. The risk is elevated in environments with weak password policies, shared accounts, or excessive user permissions granted during plugin setup.

Remediation

Update the Omnisend Email Marketing for WooCommerce plugin to the first version after 1.19.0 that includes security fixes. Verify the exact patched version against the official Omnisend advisory or WordPress plugin repository. Additionally, review and restrict user role permissions to follow the principle of least privilege, ensuring that subscriber management tasks are only assigned to necessary personnel.

Patch guidance

Check the WordPress plugin dashboard or Omnisend's official security advisory for the available patched version. Apply the update immediately after validating it in a staging environment to ensure compatibility with your WooCommerce configuration. After patching, conduct a brief audit of recent user activity logs to identify any unauthorized modifications to subscriber data that may have occurred while the plugin was vulnerable.

Detection guidance

Monitor access logs and audit trails for unusual modifications to subscriber lists, segment rules, or email campaign settings by accounts that do not normally perform such operations. Review user role assignments to identify any overly permissive accounts. Consider enabling security plugins that track changes to WooCommerce and plugin settings, and alert on suspicious administrative activities.

Why prioritize this

While the CVSS score is MEDIUM and exploitation requires authentication, the direct impact on data integrity and the ease of exploitation post-authentication make this a priority for any organization using this plugin. The absence of KEV listing suggests limited real-world weaponization currently, but the accessibility of the attack should not be underestimated given the prevalence of WooCommerce installations.

Risk score, explained

The CVSS 3.1 score of 5.4 reflects a network-accessible vulnerability with low attack complexity and low privilege requirements. The impact is primarily to integrity (alteration of subscriber data) and availability (potential disruption of email marketing operations), but not confidentiality. The score accurately represents a MEDIUM severity issue—not critical, but significant enough to warrant prompt patching and compensating controls.

Frequently asked questions