Reported vulnerability

Omnisend for WooCommerce <= 1.18.0 - Unauthenticated Omnisend Account Takeover via Predictable Connect Token

Q: Which versions of Email Marketing for WooCommerce by Omnisend are affected?

Wordfence lists these affected versions: Start version unspecified, through 1.18.0. Use the version checker above to compare your installed release with this report.

Q: Is a fix available for Email Marketing for WooCommerce by Omnisend?

Wordfence reports a fix for this issue in Email Marketing for WooCommerce by Omnisend. It lists these fixed versions: 1.18.1. Back up your website and test the recommended update before applying it to your live site.

Q: Where can I find my installed plugin version?

In WordPress, open Plugins > Installed Plugins and find the version shown beneath the plugin name.

Published 13 May 2026

Updated 13 May 2026

CVE-2026-42668

Compare your installed software with the affected versions below. Follow the source’s remediation guidance and test an available update after taking a backup. A database entry describes a reported issue; it does not establish whether a particular website has been compromised.

Does this affect my version?

Check your installed version against this advisory. This compares the report’s version ranges and does not scan your website.

Wordfence advisory

high · CVSS 7.5

The Omnisend for WooCommerce plugin for WordPress is vulnerable to an unauthenticated account takeover via insufficiently random values in versions up to, and including, 1.18.0. This is due to the generate_install_url() function deriving the OAuth connect token solely from the Unix timestamp at page-load time (hash('sha256', time())), which yields only ~86,400 distinct values per day and is trivially brute-forceable. This makes it possible for unauthenticated attackers to predict the connect token, authenticate to the POST /wp-json/omnisend-api/v1/connect REST endpoint, and replace the store's omnisend_api_key and brand_id with attacker-supplied values, redirecting all customer PII synchronization, order webhooks, and marketing communications to the attacker's Omnisend account.

Severity vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

Email Marketing for WooCommerce by Omnisend

Software: plugin · omnisend-connect
Affected versions: Start version unspecified, through 1.18.0
Fix availability: Fix available
Fixed versions: 1.18.1

Recommended action

Update to version 1.18.1, or a newer patched version

Further references (1)

wordfence.com/threat-intel/vulnerabilities/id/092061a5-5315-4401-8503-6153f660acdc?source=api-prod

Data sources and licences

Defiant hereby grants you a perpetual, worldwide, non-exclusive, no-charge, royalty-free, irrevocable copyright license to reproduce, prepare derivative works of, publicly display, publicly perform, sublicense, and distribute this software vulnerability information. Any copy of the software vulnerability information you make for such purposes is authorized provided that you include a hyperlink to this vulnerability record and reproduce Defiant's copyright designation and this license in any such copy.

Read licence terms

CVE Usage: MITRE hereby grants you a perpetual, worldwide, non-exclusive, no-charge, royalty-free, irrevocable copyright license to reproduce, prepare derivative works of, publicly display, publicly perform, sublicense, and distribute Common Vulnerabilities and Exposures (CVE®). Any copy you make for such purposes is authorized provided that you reproduce MITRE's copyright designation and this license in any such copy.

Read licence terms

Source: Wordfence

Need help fixing this issue?

Get help checking your site, applying an available update and resolving any problems after updating.

Get help with this issue

Questions about this vulnerability

Which versions of Email Marketing for WooCommerce by Omnisend are affected?

Wordfence lists these affected versions: Start version unspecified, through 1.18.0. Use the version checker above to compare your installed release with this report.

Is a fix available for Email Marketing for WooCommerce by Omnisend?

Wordfence reports a fix for this issue in Email Marketing for WooCommerce by Omnisend. It lists these fixed versions: 1.18.1. Back up your website and test the recommended update before applying it to your live site.

Where can I find my installed plugin version?

In WordPress, open Plugins > Installed Plugins and find the version shown beneath the plugin name.

Does an affected version mean my website has been hacked?

An affected version means the installed release matches a vulnerability described in this report. It does not show whether anyone has exploited it on your website. The checker compares version numbers with stored reports; it does not inspect your website.

These reports cover at least one of the same plugins, themes or WordPress core. Check each report’s affected versions separately.

Back to vulnerability database